Fast Turn Fittings
Bolt Gauge & Thread Pitch Gauge - Metric and SAE
Bolt Gauge & Thread Pitch Gauge - Metric and SAE
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The Fast Turn Fittings bolt gauge is a bolt size gauge and thread pitch gauge in one tool. Don't see a kit for your application? Use it to measure the diameter, thread pitch and length of the bolts and nuts on your car, then order matching titanium hardware the first time.
Free shipping within the USA. Most orders ship within 1 business day.
What It Measures
- Bolt diameter: Metric holes from 3 mm to 22 mm and SAE holes from #4 to 1 inch.
- Thread pitch (back side): Thread pitch grooves for both metric and SAE bolts. Slot your bolt's threads into the grooves to find the one that matches.
- SAE nut size: Posts for #6, #8, #10, 1/4", 5/16", 3/8", 7/16", 1/2", 9/16" and 5/8". Push a nut onto the posts to find the one it fits, which gives you the nut's diameter.
- Thread pitch reference chart: Standard coarse and fine pitches for metric bolts from 6 mm to 22 mm, and UNC/UNF threads per inch for SAE sizes.
- Length: Built-in millimeter and inch rulers along the edges of the gauge.
UNC vs. UNF
SAE (inch) hardware comes in two common thread types. UNC stands for Unified National Coarse, which has fewer, deeper threads per inch. UNF stands for Unified National Fine, which has more threads per inch. Most automotive bolts use fine threads (UNF), while European cars often use a mix of fine and coarse threads. Two bolts can share the same diameter but use different threads, so check the thread pitch as well as the diameter before ordering.
How to Use the Bolt Gauge
- Find the diameter: Slide the bolt's threads into the labeled holes until you find the one where it fits snugly with no side play. For SAE nuts, push the nut onto the posts to find the one it fits.
- Find the thread pitch: Flip the gauge over and slot the bolt's threads into the metric or SAE pitch grooves until they line up cleanly with no gaps.
- Measure the length: Line up the underside of the bolt head with the zero mark on the ruler and read where the tip ends. For countersunk bolts, measure the total length including the head.
- Order your hardware: Shop our individual titanium hardware in your size.
Step-by-Step Tutorial Included
Every bolt gauge comes with printed instructions. Scan the QR code on the back of the gauge to open our How to Measure Hardware tutorial, which walks through each measurement with photos and includes a size chart and FAQ.
Specifications
- Metric diameter range: 3 mm to 22 mm
- SAE diameter range: #4 to 1 inch
- Thread pitch grooves: Metric and SAE
- SAE nut posts: #6 to 5/8 inch
- Rulers: Millimeter and inch
- SKU: DUB-005
What's Included
- 1 bolt gauge
- Printed instructions
Bolt Gauge FAQ
How do I find out what size bolt I have?+
You need three measurements: diameter, thread pitch and length. Find the diameter with the gauge's holes, the thread pitch with the grooves on the back, and the length with the built-in ruler. Together they give you a size like M8 x 1.25 x 20 mm.
Does the bolt gauge measure both metric and SAE bolts?+
Yes. It has metric holes from 3 mm to 22 mm, SAE holes from #4 to 1 inch, and thread pitch grooves for both metric and SAE threads.
What's the difference between metric and SAE thread pitch?+
Metric thread pitch is the distance between threads in millimeters. An M8 x 1.25 bolt has threads 1.25 mm apart. SAE threads are measured in threads per inch (TPI), so a 5/16-24 bolt has 24 threads per inch.
Can I measure nuts with it?+
Yes, SAE nuts. Push the nut onto the posts to find the one it fits, which gives you the nut's diameter.
How do I learn to use it?+
Printed instructions come with every gauge, and the QR code on the back opens our step-by-step How to Measure Hardware tutorial.
Does the bolt gauge ship free?+
Yes. The bolt gauge ships free within the USA, and most orders ship within 1 business day.
What if there's no hardware kit for my car?+
Measure the bolts you want to replace with the gauge, then order them individually from our titanium hardware selection. Questions about sizing? Email us at sales@fastturnfittings.com.
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