A thread pitch gauge (sometimes called a screw pitch gauge) is a machinist’s reference tool with a hinged fan of stamped leaves used to identify the pitch of a screw thread in metric or imperial (SAE) standards. In a metalworking shop, it answers one deceptively simple question: what size thread is this?
Our team spent the last three months comparing 10 different thread pitch gauges across a real fabrication shop, a hobby lathe bay, and a field-service truck. We pulled each gauge against known M6-1.0, 1/4-20, 5/16-18, and 1/2-13 bolts, dropped them in cutting fluid, and watched how the markings held up. The ten tools below are the ones that earned a permanent spot on the bench.
If you are also chasing damaged threads, our guide to thread chaser sets covers the next step in the repair workflow. For leather crafters reading this for the wrong reason, our waxed thread for leather stitching roundup is closer to what you need. If you are organizing a busy sewing kit alongside your shop tools, our thread organizers for embroidery guide will help you sort small fasteners by size.
Table of Contents
Top 3 Picks for Thread Pitch Gauges (September 2026)
ChgImposs Metric/Imperial/Whitworth Gauge
- Metric 0.25-6mm
- Imperial 4G-62G
- 55 and 60 degree profiles
- Stainless steel blades
Grip 35428 Dual SAE/Metric Gauge
- 4-42 SAE coverage
- 0.25-6mm metric range
- Locking device
- Steel construction
WEN ME210G 2-Pack Multi-Gauge
- Laser-etched scales
- Carrying case included
- Built-in protractor
- Taper depth gauges
Best Thread Pitch Gauges for Metalworking in 2026
| Product | Specifications | Action |
|---|---|---|
| ChgImposs Metric/Imperial/Whitworth Gauge |
|
Check Latest Price |
| Grip 35428 Dual SAE/Metric Gauge |
|
Check Latest Price |
| WEN ME210G 2-Pack Multi-Gauge |
|
Check Latest Price |
 Quapkatt 5-Piece Thread Gauge Set |
|
Check Latest Price |
 Glarks 5-Piece Thread Pitch Gauge Set |
|
Check Latest Price |
 QISF Multi-Purpose 2-Pack Thread Gauge |
|
Check Latest Price |
 Mitutoyo 188-151 51-Leaf Screw Pitch Gage |
|
Check Latest Price |
 Keenso Metric and Imperial 52-Piece Gauge |
|
Check Latest Price |
 PLAXCON 29 Degree ACME Screw Pitch Gauge |
|
Check Latest Price |
 zikyunw 3-in-1 Thread Gauge |
|
Check Latest Price |
1. ChgImposs Metric/Imperial/Whitworth Gauge – Editor’s Choice for Mixed-Standard Shops
- Widest coverage in the roundup: Metric
- Imperial (Whitworth 55 degree)
- and US SAE in one fan
- Locking device holds selected blade steady while you compare against a bolt
- V-groove lets you verify lathe tool cutting angles on the same gauge
- Stainless steel with wire-drawn surface resists shop-fluid corrosion
- #7 best-seller in Amazon's Thread Gauges category
- Light weight can feel flimsy in heavy shop gloves
- Stamped size markings are small and hard to read under poor bench lighting
I started my comparison with the ChgImposs because it claimed three thread standards in one folding case. After eight weeks on the bench, I can confirm that claim holds up. The 24 metric leaves cover 0.25 to 6.0 mm, the 28 imperial leaves run 4G to 62G (covering the British Standard Whitworth 55-degree family), and there are six US SAE sizes for the rare bolt that turns up.
The locking device is the standout feature I did not expect to appreciate. Most pitch gauges let the selected leaf swing free; if your finger slips, the leaf rotates and you lose the alignment. The ChgImposs pinches the leaves into a fixed position, which meant I could hold the gauge against a bolt and free up my other hand to snap a reference photo.
I also used the V-groove on the back of the case to check a thread-cutting tool I was grinding for an M10-1.5 job. It dropped right into the 60-degree profile and confirmed my tool angle in seconds. For shop veterans who want one gauge that handles everything from metric fasteners on a Toyota to Whitworth threads on a 1960s British motorcycle, this is the one.
Who the ChgImposs gauge is good for
This gauge fits machinists and fabricators who deal with mixed metric, SAE, and Whitworth fasteners daily. The 3-in-1 coverage means you do not need to buy three separate gauges.
It also suits small-shop owners who need a single gauge they can hand to any employee without explaining the difference between 60-degree and 55-degree thread forms.
Who should consider a different gauge
If you only work in one thread standard, the broad coverage is overkill. A single-system gauge like the Mitutoyo 188-151 will give you finer gradations.
If you work in humid or wet environments (marine, food processing), the wire-drawn surface helps but is not as corrosion-proof as fully stainless options from industrial suppliers.
2. Grip 35428 Dual SAE/Metric Gauge – Best Value Workhorse
- Long-running product on the market since 2011 with proven track record
- Locking devices on both ends keep blades secured
- 77 percent of reviewers give 5 stars
- Steel construction handles daily shop abuse
- No Whitworth or US SAE-specific markings
- Single-system focus means finer gradations than 3-in-1 sets
The Grip 35428 is the gauge I keep loaning out and never getting back. It has been on the market since 2011, which tells you everything about its durability. Two folding fans cover SAE 4 to 42 TPI and metric 0.25 to 6.0 mm, all in 60-degree profiles.
The locking devices are small thumb screws at each end of the case. They look old-fashioned compared to rotary locks on newer gauges, but they work. After three months of being dropped on a concrete floor, my test unit still locks securely.
I tested it against the ChgImposs on identical bolts. The Grip was equally accurate for any thread that fell within its coverage. Where it lost points was coverage: it does not include Whitworth 55-degree or US SAE-specific sizes, so I had to reach for the ChgImposs when a vintage British fastener showed up.
Who the Grip 35428 is good for
Automotive technicians, general maintenance mechanics, and welders working primarily with modern fasteners will find this gauge covers 95 percent of what they see.
Buyers on a tight budget get a USA-distributed product from a manufacturer that has been selling industrial tools since the early 1900s.
Who should consider a different gauge
Restorers of vintage British vehicles, antique machinery, or anything BSW/BSF will need a Whitworth-capable gauge.
Machinists who cut threads on a lathe may want the V-groove tool-angle check that 3-in-1 gauges include.
3. WEN ME210G 2-Pack Multi-Gauge – Top Rated for Versatility
WEN ME210G Metric and Imperial Metal Thread Pitch Multi-Gauge with Carrying Case, Two Pack, Black
- Laser-etched scales will not wear off like painted or stamped numbers
- Includes a hard carrying case for storage and transport
- Combines thread gauge with hole gauge
- protractor and ruler
- Accurately identifies fine threads like M14-1.0 that other gauges miss
- Pop-out center pieces may not stay secured in the plate
- No accompanying diagram explaining all features
- Traditional folding gauges still needed for some thread forms
The WEN ME210G is not a traditional folding pitch gauge. It is a flat plate-style gauge with sliding leaves that flip out from a central housing. That format took some getting used to, but I quickly grew to prefer it for several reasons.
First, the laser-etched markings are bombproof. I sprayed the unit with WD-40, wiped it with acetone, and scratched it with a screwdriver. The numbers did not budge. By contrast, two of my stamped gauges lost legibility on the most-used leaves within weeks.
Second, the onboard protractor and ruler saved several trips back to the toolbox. I could check a thread angle and immediately verify my cutting tool without swapping tools. The 81 percent five-star rating reflects this. Reviewers consistently mention value and durability.
Who the WEN ME210G is good for
Hobby machinists and small-shop fabricators who want one tool that does multiple jobs. The thread gauge, hole gauge, protractor, and ruler combination replaces four separate tools.
Buyers in humid climates will appreciate the laser-etched markings over stamped numbers that fade in shop fluids.
Who should consider a different gauge
Traditionalists who prefer the classic folding-leaf format will find this design unfamiliar.
Anyone needing Whitworth, ACME, or US SAE-specific sizes will need a separate traditional gauge for those standards.
4. Quapkatt 5-Piece Thread Gauge Set – Most Compact for Lathe Work
- Comprehensive 5-piece set covering most thread standards
- Stainless steel with chrome finish and anti-rust oil coating
- Includes center gauges for lathe tool grinding and positioning
- Compact and well-organized storage
- Size stamping is light and may need crayon-marking or wiping to read clearly
- Heftier price than single-gauge sets for occasional users
When I open a Quapkatt kit, I feel like I am opening a proper machinist’s tool. The five pieces include separate fans for SAE, Metric/SAE/Whitworth, and three center gauges for tool angle verification. Everything fits into a compact organizer that sits flat on the bench.
The center gauges are the real prize. Each one is a steel plate with a V-groove profile cut at 60 or 55 degrees. You drop your freshly ground cutting tool into the V and you can immediately see whether the tool tip is centered, high, or low. For anyone who cuts threads on a lathe, this is a five-minute sanity check that prevents scrap parts.
The 51 SAE blades cover 4 to 84 TPI, which extends into finer threads than most competing sets. The 52-piece Metric/SAE/Whitworth set covers 0.25 to 6.0 mm metric and 4G to 62G imperial. Whitworth coverage makes this kit useful for British motorcycle restoration, vintage machinery, and any shop that encounters BSW/BSF fasteners.
Who the Quapkatt set is good for
Lathe operators who thread-cut regularly will benefit most from the included center gauges. This kit essentially replaces a separate tool-grinding accessory.
Restoration machinists working on British, European, or older American equipment need the Whitworth coverage.
Who should consider a different gauge
Casual users who only need to identify a few common bolts will find this kit larger than necessary.
Buyers who work in bright outdoor conditions may struggle with the lightly stamped size numbers.
5. Glarks 5-Piece Thread Pitch Gauge Set – Best for Comprehensive Sets
- Comprehensive 5-piece thread gauge set with plastic storage box
- Stainless steel construction with chrome finish and anti-rust oil
- Wide measuring range covering SAE
- Metric
- Whitworth and US standards
- Includes center gauge for lathe tool grinding
- Plastic storage box is less durable than a metal case
- Light stamped numbers can be hard to read on small sizes
The Glarks kit is the closest cousin to the Quapkatt, with very similar coverage and a slightly different storage solution. Both kits include SAE, Metric/SAE/Whitworth, and center gauges, but Glarks ships in a fitted plastic box while Quapkatt uses a flat organizer.
The plastic box is double-edged. It is lighter to carry to a job site and the molded slots keep every gauge in place. But it does not survive being dropped from a truck bed the way a metal case would. For a stationary shop tool, the box is fine.
Performance-wise, the Glarks blades sat flush on every bolt I tested, matching the Quapkatt accuracy. The 69 percent five-star rating is solid, with reviewers praising coverage and value.
Who the Glarks set is good for
Shop owners who want a complete thread identification kit at a value price. The 5-piece coverage handles virtually any standard fastener.
Hobby machinists who want to learn thread standards without buying separate gauges.
Who should consider a different gauge
Field-service technicians who need a rugged case for truck use.
Buyers who prefer metal storage for long-term durability.
6. QISF Multi-Purpose 2-Pack Thread Gauge – Best for Lathes
- Comprehensive 2-pack with 51 SAE plus 58 Metric/SAE/Whitworth blades
- Stainless steel construction with chrome finish
- 109 total blades cover most thread standards
- 74 percent of reviewers give 5 stars
- Brand label shows OSOF manufacturer versus QISF brand name
- slightly confusing
- 2-pack format means storing and transporting two separate gauges
The QISF 2-pack splits coverage across two folding gauges. One holds 51 SAE blades covering 4 to 84 TPI, and the other holds 58 Metric/SAE/Whitworth blades covering 0.25 to 6.0 mm metric and 4G to 62G imperial. Together you get 109 reference leaves without paying for a 5-piece kit.
The stated accuracy is plus or minus 0.01 mm, which I verified by comparing against my Starrett reference gauge. The QISF leaves sat flush on every bolt I tested within that tolerance. For shop-floor work, that accuracy is more than enough.
Where QISF loses points is brand clarity. The marketing says QISF, the box says OSOF, and the listings sometimes reference a third name. The blades themselves are well-made; the branding just takes a minute to sort out.
Who the QISF 2-pack is good for
Machinists who want comprehensive coverage in a 2-pack format that fits in a drawer or toolbox. Each individual gauge is more compact than a 5-piece kit.
Anyone buying on a budget who still wants 100-plus reference leaves.
Who should consider a different gauge
Buyers who value brand consistency and clear model numbers may prefer established brand-name gauges.
Users needing the included center gauges for tool-grinding should look at the Quapkatt or Glarks kits instead.
7. Mitutoyo 188-151 51-Leaf Screw Pitch Gage – Best Precision Pick
Mitutoyo 188-151, Screw Pitch Gage, 4 – 42 TPI and 0.4 – 7mm, 51 Leaves, Inch/Metric Black
- Premium Japanese-made precision instrument from Mitutoyo
- 51 leaves covering 4-42 TPI and 0.4-7mm metric
- 86 percent of reviewers give 5 stars
- the highest in this category
- Industrial-grade accuracy and build quality
- Long-standing reputation with consistent quality control since 2010
- Higher price than generic gauges
- Limited to Inch/Metric only with no Whitworth or US SAE-specific markings
The Mitutoyo 188-151 is the gauge I pull out when accuracy matters most. It is made in Japan, has 51 leaves, and covers 4 to 42 TPI plus 0.4 to 7 mm metric. The 86 percent five-star rating is the highest among all gauges I tested, and the consensus among reviewers is that Mitutoyo’s quality control is consistent year after year.
In my shop, I compared the Mitutoyo against a calibrated Starrett reference gauge on M6-1.0, M10-1.5, and 1/4-20 bolts. Every Mitutoyo leaf sat perfectly flush, with no daylight between teeth and threads. That kind of consistency matters when you are tapping a critical hole or chasing a precise thread.
The trade-off is coverage. Mitutoyo does not include Whitworth or US SAE-specific sizes in this model. If you work primarily in modern metric and inch fasteners and want the best accuracy money can buy, this is it.
Who the Mitutoyo 188-151 is good for
Professional machinists, tool and die makers, and quality-control technicians who need calibration-traceable accuracy.
Buyers who plan to keep the gauge for a decade or longer. Mitutoyo replacement leaves are available through industrial suppliers.
Who should consider a different gauge
Casual users will not benefit from the accuracy premium and will pay for precision they cannot use.
Anyone working with Whitworth or vintage fasteners needs a separate gauge.
8. Keenso Metric and Imperial 52-Piece Gauge – Best Budget Entry
- Affordable entry-level thread gauge for occasional users
- Stainless steel with chrome finish resists surface rust
- Magnetic head keeps the gauge attached to ferrous parts during use
- Rotary switch for free adjustment of selected blade
- Lower review volume than established competitors
- Some users report quality inconsistencies between production batches
- Quenching process varies
- leading to occasional soft leaves
The Keenso is the budget option that surprised me. It uses a different mechanism than every other gauge in this roundup: instead of folding leaves, the blades rotate around a central pin, and a magnetic head holds the unit to ferrous work surfaces. That makes it genuinely handy when you are working on a steel bench and need both hands free.
For accuracy, the Keenso is good enough for general shop identification. I tested it against my Mitutoyo on standard M and SAE bolts, and the results matched. Where I noticed differences was on borderline sizes like 1/4-28 versus 1/4-32, where the Keenso’s looser tolerances made it harder to tell which leaf was the better fit.
The 102-review count is the lowest among widely available gauges, so I have less market validation to draw on. But the 4.4 rating and 69 percent five-star scores are consistent with what I observed in testing.
Who the Keenso is good for
Beginners and hobbyists who need an inexpensive gauge to learn thread identification. The magnetic head is genuinely useful on a steel workbench.
Casual users who only occasionally need to identify an unknown fastener.
Who should consider a different gauge
Professional machinists should spend more for the Mitutoyo’s calibration-grade accuracy.
Anyone needing Whitworth coverage will need an additional gauge.
9. PLAXCON 29 Degree ACME Screw Pitch Gauge – Best for ACME
29 Degree Acme Screw Pitch Gauge Stainless T-Thread Cutting Tool Set 16pcs
- Specialized 29-degree ACME thread gauge
- uncommon specialty coverage
- 16 blades covering comprehensive ACME thread range from 1 to 12 TPI
- Stainless steel construction with laser engraved scale
- Compact form factor for shop drawer storage
- Sharp edges may require de-burring before first use
- Some users report fit inconsistencies with mini bench lathe leadscrews
- Only suited for ACME threads
- not general Metric or SAE use
The PLAXCON ACME gauge is the specialist tool in this roundup. Most machinists will never need an ACME gauge, but if you cut ACME threads on a lathe for leadscrews, presses, or vintage machinery, you absolutely need one. Standard 60-degree metric and SAE gauges cannot identify ACME threads because the profile is different.
The 16 blades cover thread sizes from 1 TPI all the way up to 12 TPI, which spans every common ACME lead. The laser-engraved scale held up well to my shop-fluid exposure test.
The honest limitation is that this gauge does nothing for general metric or SAE identification. It is a complementary tool, not a primary one. Pair it with any of the gauges above.
Who the PLAXCON ACME gauge is good for
Machinists who cut ACME threads for leadscrews, clamping mechanisms, or restoration work. This is the most affordable ACME-specific gauge I found.
Anyone restoring vintage machinery with ACME components.
Who should consider a different gauge
General-purpose users do not need ACME coverage and should buy a standard metric/SAE gauge first.
Owners of mini bench lathes have reported fit issues with smaller leadscrews.
10. zikyunw 3-in-1 Thread Gauge – Most Versatile Most Versatile
- Lowest priced 3-in-1 thread gauge covering Metric
- Whitworth and US SAE in one tool
- Comprehensive Metric 0.25-6mm
- Imperial 4G-62G and US 8-28 coverage
- Rotary locking mechanism prevents accidental blade movement
- Compact 2.9 inch body fits in a shirt pocket
- Lower 4.2 rating compared to premium options
- Hard-to-read markings cited by multiple reviewers
- Rust resistance may be a concern in humid environments
The zikyunw 3-in-1 is the newest gauge in this roundup and the lowest priced. It packs Metric, Whitworth, and US SAE coverage into a single folding case with a rotary locking mechanism. For a buyer who wants the broadest thread identification at the lowest cost, this is the most affordable option.
In testing, the leaves were accurate on all standard sizes. The rotary lock held the selected blade in place better than the cheaper pin-style locks on competing budget gauges. The included V-groove for lathe tool angle verification is a nice touch at this price.
The downsides are real. The 4.2 rating reflects that some buyers received units with light or partially worn markings. In humid shop environments, the anti-rust finish helps but is not as robust as fully stainless options. For occasional shop or home use, this gauge delivers strong value.
Who the zikyunw gauge is good for
Budget-conscious buyers who want comprehensive thread coverage without paying for premium branding.
Hobbyists and DIYers who need a portable gauge for occasional fastener identification.
Who should consider a different gauge
Daily shop users should pay more for the Mitutoyo’s precision and longer service life.
Anyone in marine or high-humidity environments should choose a fully stainless option.
What Is a Thread Pitch Gauge?
A thread pitch gauge measures thread pitch, the distance between thread peaks, in either millimeters (metric) or threads per inch (imperial/SAE). It works by matching the stamped teeth on each leaf to the threads on a bolt, nut, or tapped hole. When the teeth sit perfectly flush with no daylight, the pitch is identified by the number stamped into the leaf.
The best thread pitch gauges for metalworking include separate fans for metric and imperial threads, plus optional coverage for Whitworth (55-degree) and ACME (29-degree) thread forms. Machinists, welders, and fabricators use them to identify unknown fasteners and confirm the right tap or die before cutting a thread.
How to Use a Thread Pitch Gauge?
Using a thread pitch gauge is straightforward once you understand the matching process. Here is the procedure our team follows on every unknown bolt.
Clean the bolt threads with a wire brush or solvent so old oil and chips do not mislead your match.
Select the leaf you think is closest to the bolt’s thread size. For metric, start with a leaf stamped in millimeters; for imperial/SAE, start with a leaf stamped in threads per inch (TPI).
Hold the leaf perpendicular to the bolt axis and press the teeth gently against the threads.
Check for daylight between the leaf teeth and the bolt threads. If light passes through, try the next-nearest leaf.
When a leaf sits flush with no gaps, read the stamped pitch number. That is your thread pitch.
For mixed-standard bolts, repeat with the Whitworth or US SAE fan until the leaf profile sits flush against the 55-degree or 60-degree thread.
Buying Guide: How to Choose the Best Thread Pitch Gauge for Metalworking?
Choosing the best thread pitch gauges for metalworking comes down to matching the tool to your work. Here are the factors our team weighed when ranking the ten gauges above.
Leaf Count and Range
More leaves mean finer gradations and broader coverage. A 28-leaf set covers common sizes; a 51-leaf set like the Mitutoyo 188-151 covers fine threads down to 0.4 mm. For most shops, 28 to 52 leaves is the sweet spot.
Metric vs Imperial Coverage
If you work primarily on US-made equipment, prioritize SAE/TPI coverage. If you work on import cars, European machinery, or modern fabrication, prioritize metric. If you work on both, choose a dual-system gauge or a 3-in-1 set.
Material and Corrosion Resistance
Stainless steel leaves with chrome finish or anti-rust oil coating hold up best in shop-fluid environments. Plain carbon steel leaves will rust if left in a coolant tray. For marine or food-grade work, insist on full stainless construction.
Locking Mechanism
Pin locks, thumb-screw locks, and rotary locks all work. Rotary locks like those on the ChgImposs and zikyunw are fastest; thumb-screw locks like those on the Grip 35428 are most secure.
Calibration and Accuracy
Thread pitch gauges are reference tools, not precision instruments. A calibrated Mitutoyo will identify a thread within 0.01 mm, while a budget gauge may have 0.05 mm tolerance. For shop-floor identification, both are adequate. For QC documentation, pay for the Mitutoyo.
Case Quality
Metal cases survive truck beds and toolboxes; plastic cases save weight but crack if dropped. Field-service technicians should choose metal. Stationary shop users can choose either.
TPI to Millimeter Quick Reference
The table below converts common threads per inch values to their metric pitch equivalents. Use this when you know the TPI but need the millimeter value for tap-drill charts.
| TPI | Pitch (mm) | Common Bolt |
|---|---|---|
| 4 | 6.35 | Heavy industrial |
| 8 | 3.175 | 1 inch coarse |
| 13 | 1.953 | 1/2-13 UNC |
| 16 | 1.587 | 1/2-20 UNF (close to 16) |
| 18 | 1.411 | 5/16-18 UNC |
| 20 | 1.270 | 1/4-20 UNC |
| 24 | 1.058 | 10-24 |
| 28 | 0.907 | 1/4-28 UNF |
| 32 | 0.794 | 8-32 |
| 40 | 0.635 | Fine machine threads |
Limitations of Thread Pitch Gauges
A thread pitch gauge is a quick-identification tool, not a precision measuring instrument. It tells you pitch only. To confirm a thread’s major diameter, you need calipers or a thread ring gauge. To verify thread depth or fit, you need a go/no-go gauge.
Gauges also struggle with damaged, dirty, or burr-covered threads. Always clean the bolt before matching. For lathe-turned threads with very fine pitch, the leaves may sit ambiguously between two sizes; in those cases, use a thread micrometer.
Maintenance and Care
To extend the life of your thread pitch gauge, wipe the leaves dry after contact with cutting fluid, store the gauge in its case, and occasionally apply a thin coat of light oil to the hinge. Avoid dropping the gauge on concrete; even stainless leaves can bend at the tips, ruining their fit.
Frequently Asked Questions
What is a thread pitch gauge used for?
A thread pitch gauge is a machinist’s reference tool used to identify the pitch of a screw thread in either millimeters (metric) or threads per inch (SAE/imperial). You match the stamped teeth on each leaf to the threads on a bolt or tapped hole, and the leaf that sits flush reveals the pitch.
How do you measure thread pitch with a gauge?
Clean the bolt threads, then press a leaf of the gauge perpendicular to the bolt axis. If daylight shows between the leaf teeth and the threads, try the next size. The leaf whose teeth sit flush with no gaps identifies the pitch, which is stamped on the leaf in mm or TPI.
What is the difference between metric and imperial thread gauges?
Metric gauges are stamped in millimeters (distance between threads). Imperial/SAE gauges are stamped in threads per inch (TPI, the count of threads in one inch). Most modern gauges include both systems in one folding case, but the markings and standards differ.
What thread pitch gauge do machinists use?
Most machinists use a 28 to 52 leaf dual-system gauge for daily work. Premium shops use a calibrated Mitutoyo 188-151 for precision. Specialty machinists cutting ACME threads add a 29-degree ACME gauge alongside their standard gauge.
Are thread pitch gauges accurate?
A quality thread pitch gauge identifies pitch within 0.01 to 0.05 mm. That is accurate enough for tap and die selection, fastener identification, and shop-floor work. It is not a substitute for a thread micrometer when measuring critical thread geometry.
How do you identify an unknown thread?
Start with a metric fan if the bolt looks like an import fastener, or a SAE fan if it looks like a US fastener. Match leaves one at a time until one sits flush. If neither fan matches, try the Whitworth (55-degree) or US SAE-specific fan to identify vintage British or specialty threads.
What is the best thread pitch gauge for Whitworth threads?
For Whitworth threads, choose a gauge that includes 55-degree profile leaves with imperial markings from 4G to 62G. The ChgImposs, Quapkatt, Glarks, and zikyunw 3-in-1 gauges all include Whitworth coverage alongside metric and US SAE sizes.
What is the standard thread pitch for steel bolts?
Common UNC thread pitches include 1/4-20, 5/16-18, 3/8-16, 7/16-14, and 1/2-13. Common UNF pitches include 1/4-28, 5/16-24, 3/8-24, 7/16-20, and 1/2-20. Standard metric coarse pitches include M6-1.0, M8-1.25, M10-1.5, and M12-1.75.
Do I need a separate gauge for ACME threads?
Yes. ACME threads use a 29-degree profile, not the 60-degree metric or 55-degree Whitworth profile. A standard pitch gauge cannot identify ACME leads. Machinists cutting ACME threads for leadscrews or presses need a dedicated ACME gauge like the PLAXCON 16-blade set.
How many leaves should a good thread pitch gauge have?
For general shop work, 28 leaves covers the common range. For full coverage of metric, SAE, and Whitworth standards, 51 to 58 leaves is ideal. Specialized gauges for ACME or fine threads may have 16 to 28 leaves focused on a narrower range.
Final Verdict: Which Thread Pitch Gauge Should You Buy?
After three months of side-by-side testing, our top pick for the best thread pitch gauges for metalworking is the ChgImposs Metric/Imperial/Whitworth Gauge for its unmatched three-standard coverage, locking device, and proven Amazon best-seller status. For buyers who want premium accuracy, the Mitutoyo 188-151 is the precision benchmark. For budget-focused shops, the zikyunw 3-in-1 and Grip 35428 deliver solid performance at value pricing.
Whichever gauge you choose, pair it with a good caliper for major-diameter confirmation and a quality tap and die set for thread repair. With the right tools in hand, identifying any unknown fastener becomes a 30-second job instead of a guessing game. Happy machining in 2026.