screw size converter

Workshop Converter

Screw Size Converter

Convert screw sizes between gauge, millimetres and inches instantly.

mm
in
Gauge No. 6
Metric Diameter 3.5mm
Inch Diameter 0.138in
No. 6 screw is approximately 3.5mm or 0.138 inches in diameter.
Gauge Approx mm Approx inches
No. 01.5mm0.060in
No. 22.2mm0.086in
No. 42.9mm0.112in
No. 63.5mm0.138in
No. 84.2mm0.164in
No. 104.8mm0.190in
No. 125.5mm0.216in
No. 146.3mm0.250in
Note: Screw sizes vary by standard, thread type, manufacturer and country. Use this as a helpful guide and always check the exact screw specification before drilling, tapping or ordering fixings.

Screw Size Converter

Need to convert screw sizes quickly and accurately? Our free Screw Size Converter gives instant results for screw gauge, millimetres and inches — perfect for DIY, engineering, workshops, fixings and hardware checks.

Whether you are converting:

  • No. 6 screw to mm
  • screw gauge to inches
  • metric screw diameters
  • imperial screw sizes
  • wood screw sizes
  • pilot hole references
  • workshop fixing sizes

…our calculator makes it simple.

What Is Screw Gauge?

Screw gauge is a sizing system used to describe screw diameter. It is commonly used across:

  • wood screws
  • imperial fixings
  • DIY projects
  • joinery and carpentry
  • workshop hardware
  • older screw size charts

What Are Metric Screw Sizes?

Metric screw sizes usually describe the screw diameter in millimetres.

  • Metric sizes are shown in mm
  • Imperial sizes may use gauge numbers
  • Diameter is different from screw length
  • Thread type can affect compatibility
  • Always check the exact fixing specification

Screw Size Formula

To convert millimetres to inches:

Inches=Millimetres÷25.4

Example:

No. 6 screw = approximately 3.5mm = 0.138 inches

Common Screw Size Conversions

Gauge Approx mm Approx inches
No. 0 1.5mm 0.060in
No. 2 2.2mm 0.086in
No. 4 2.9mm 0.112in
No. 6 3.5mm 0.138in
No. 8 4.2mm 0.164in
No. 10 4.8mm 0.190in
No. 12 5.5mm 0.216in
No. 14 6.3mm 0.250in

Why Use Our Screw Size Calculator?

  • Instant live conversion
  • Converts screw gauge to mm
  • Converts screw gauge to inches
  • Converts mm and inches back to approximate gauge
  • Mobile friendly
  • Simple dark-mode design
  • Popular Screw Size Searches

People often search for:

  • No. 6 screw size in mm
  • No. 8 screw diameter
  • screw gauge to mm
  • screw size converter
  • imperial screw size chart
  • wood screw sizes
  • screw diameter in inches

Our converter is designed to answer these instantly.

DIY & Workshop Uses

Screw size conversions are commonly used for:

  • choosing fixings
  • checking screw diameter
  • pilot hole planning
  • woodworking projects
  • engineering references
  • hardware replacement
  • workshop measurements
  • Fixing & Hardware Uses

This converter is also useful for:

  • matching old screws
  • ordering replacement fixings
  • checking imperial and metric sizes
  • carpentry and joinery
  • home repairs
  • technical size comparisons

Use WhatsThisIn.com to convert screw sizes instantly with precision.