SAE to Metric Calculator & Metric to Standard

Convert a measurement from SAE to metric or metric to standard SAE using the calculator below. Learn more about SAE and metric measurements and refer to the conversion chart below.

How to Convert SAE to Metric

SAE, or standard, and metric sockets, wrenches, and fasteners are both commonly used, and the difference between them is significant. Before we cover how to convert SAE to metric, it’s important to understand what these terms actually mean.

SAE stands for Society of Automotive Engineers,[1] and is based on standard imperial and U.S. customary measurements. It’s based on measurements in inch fractions and is most commonly used in the United States.

Metric sizes are used worldwide, and sockets and screws are primarily measured in millimeters.

You can use the chart below to convert an SAE size to metric, but you can also do the conversion by hand in a few easy steps.

Step One: Convert the Fraction to Decimal

The first step is to convert the inch fraction to a decimal. You can do this by treating the fraction as a division problem and solving.

For instance:
1/4″ = 1 ÷ 4 = 0.25″

Step Two: Convert to Millimeters

The next step is to multiply the inch decimal by 25.4 to convert it to millimeters. This is the key step for converting SAE to metric.

0.25″ × 25.4 = 6.35 mm

SAE to Metric Conversion Chart

The chart below shows SAE and equivalent metric and inch decimal measurements for common socket, wrench, and screw sizes.

SAE to metric conversion chart showing equivalent standard and metric measurements
Standard (SAE) Metric (mm) Inches (decimal)
1/32″ 0.7938 mm 0.0313″
1 mm 0.0394″
1/16″ 1.5875 mm 0.0625″
5/64″ 1.98438 mm 0.0781″
2 mm 0.0787″
3/32″ 2.3813 mm 0.0938″
7/64″ 2.7781 mm 0.1094″
3 mm 0.1181″
1/8″ 3.175 mm 0.125″
5/32″ 3.9688 mm 0.156″
4 mm 0.157″
4.5 mm 0.177″
3/16″ 4.7625 mm 0.188″
5 mm 0.197″
5.5 mm 0.216″
7/32″ 5.5563 mm 0.219″
6 mm 0.236″
1/4″ 6.35 mm 0.25″
6.5 mm 0.256″
7 mm 0.276″
9/32″ 7.1438 mm 0.281″
5/16″ 7.9375 mm 0.313″
8 mm 0.315″
11/32″ 8.7313 mm 0.344″
9 mm 0.354″
3/8″ 9.525 mm 0.375″
10 mm 0.394″
13/32″ 10.3188 mm 0.406″
11 mm 0.433″
7/16″ 11.1125 mm 0.438″
15/32″ 11.9063 mm 0.469″
12 mm 0.472″
1/2″ 12.7 mm 0.5″
13 mm 0.512″
17/32″ 13.4938 mm 0.531″
14 mm 0.551″
9/16″ 14.2875 mm 0.563″
15 mm 0.591″
19/32″ 15.0813 mm 0.594″
5/8″ 15.875 mm 0.625″
16 mm 0.63″
21/32″ 16.6688 mm 0.656″
17 mm 0.669″
11/16″ 17.4625 mm 0.688″
18 mm 0.709″
23/32″ 18.2563 mm 0.719″
19 mm 0.748″
3/4″ 19.05 mm 0.75″
25/32″ 19.8438 mm 0.781″
20 mm 0.787″
13/16″ 20.6375 mm 0.813″
21 mm 0.827″
27/32″ 21.4313 mm 0.844″
22 mm 0.866″
7/8″ 22.225 mm 0.875″
23 mm 0.906″
29/32″ 23.0188 mm 0.906″
15/16″ 23.8125 mm 0.938″
24 mm 0.945″
1″ 24.5 mm 1″

More Standard to Metric Conversions

You can use our inches to mm conversion calculator to convert SAE measurements to metric or convert these common sizes.

References

  1. SAE International, https://www.sae.org/