Bolt & Screw Identifier

Set your calipers to Millimeters (mm) for all steps.

Step 1: Head Type

Step 2: Head Markings (Optional)

Look for numbers or lines on the top of the bolt head.

Step 3: Diameter

Measure the diameter of the threaded section.

Step 4: Length

Measure from under the head to the tip.

Step 5: Thread Measurement

Take two measurements for best accuracy. Place your caliper's inner jaws in the thread grooves, measuring the inside edges.

Possible Matches

Our best guess is highlighted in green, based on the closest measurements and the most common sizes.

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