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Screw Size Converter (Gauge to Metric)

Convert screw sizes between gauge (#6-#14), metric (M3-M8), and imperial diameter.

Updated April 2026

Screw gauge

Gauge

Metric

Diameter

0.164"

Thread pitch (TPI)

Coarse: 32 TPI · Fine: 36 TPI

Head types

flat, pan, round, truss, button

Common lengths

1/2"3/4"1"1-1/4"1-1/2"2"2-1/2"3"

Metric conversion is nominal — M4 is technically 0.157" but is the closest commercial equivalent to #8. For structural use, match the exact fastener standard (ANSI B18.6.3 for inch, ISO 1478 for metric).

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What it does

#8 = M4 = .164". Gauge, metric, imperial, plus thread pitches and common lengths and head types.

Runs entirely in your browser — no upload, no account, no watermark. For more tools in this category see the full tools index.

Embed this tool on your siteShow snippet

Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.

<iframe src="https://freetoolarena.com/embed/screw-size-converter" width="100%" height="720" frameborder="0" loading="lazy" title="Screw Size Converter (Gauge to Metric)" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>

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How to use it

Enter gauge, metric, or diameter.
Read all three.
Check thread + head types.