1/8" to mm - SAE to Metric Calculator

Do you need to convert 1/8 inch to mm?

1/8 inch = 3.175 mm

If you're curious how we got that answer, here's the 1/8" to mm formula:

1 ÷ 8 × 25.4 = 3.175 mm
0.125 × 25.4 = 3.175 mm

To convert 1/8 inch to mm, divide 1 by 8 to convert the fraction to a decimal. Then, multiply that by 25.4 since there are 25.4 millimeters in one inch.

That's the formula that our calculator uses to find that 1/8 inch to millimeters is 3.175 mm.

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.

• Convert SAE to Metric
• Convert Metric to SAE

SAE Size:

inches

Metric Size:

mm

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Metric Result:

Metric Result:

 

mm

SAE Result:

Nearest Standard Measurement

 

Exact Measurement

 

Learn how we calculated this below

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On this page:

• Calculator
• How to Convert SAE to Metric
• Step One: Convert the Inch Fraction to an Inch Decimal
• Step Two: Convert the Inch Decimal to Millimeters
• SAE to Metric Conversion Chart
• More Standard to Metric Conversions
• References

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By

Joe Sexton

Joe is the creator of Inch Calculator and has over 20 years of experience in engineering and construction. He holds several degrees and certifications.

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Reviewed by

Stephen Fogel

Stephen specializes in all aspects of the automotive world and has been an automotive enthusiast since childhood. He follows the global automotive industry closely, with an eye on the latest vehicle technologies.

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Cite As:

Sexton, J. (n.d.). 1/8" to mm - SAE to Metric Calculator. Inch Calculator. Retrieved November 21, 2024, from https://www.inchcalculator.com/sae-to-metric-calculator/

How to Convert SAE to Metric

SAE, or standard, and metric sockets, wrenches, and fasteners are both commonly used, but the difference between them is significant. Before we explain 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 measurement systems. It uses measurements in inch fractions and is most commonly used in the United States.

The metric system was developed more recently and is commonly used worldwide. Metric sockets and screws are primarily measured in millimeters.

You can use the chart below to convert an SAE size to metric. You can also do the conversion by hand in a few easy steps as follows:

Step One: Convert the Inch Fraction to an Inch 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 it.

For instance:
1/4″ = 1 ÷ 4 = 0.25″

Step Two: Convert the Inch Decimal 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 measurements (in fractions) and the equivalent metric and inch decimal measurements for common socket, wrench, and screw sizes.

More Standard to Metric Conversions

You can use our inches to mm conversion calculator to convert SAE measurements to metric. You can also convert these common sizes by using the links below: