Convert Millimeters to Inches

Instantly convert millimeters (mm) to inches (in). Enter a value to see the result and the conversion formula.

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How our Millimeters to Inches unit converter works

To ensure maximum accuracy when converting Millimeters to Inches, our calculator uses a scientific pivot method. Instead of relying on a potentially inaccurate direct conversion, the system first converts mm into the base unit of the International System (the meter), then recalculates the result into in. This approach drastically reduces rounding errors.

About this conversion

Precipitation in Canada is measured in millimeters, while the US uses inches. In mechanics, switching between metric and imperial sockets is a daily reality.

When to use this conversion

Used by mechanics matching wrench sizes, or meteorologists translating Canadian rainfall data for American audiences.

Formula

Inches (in) = Millimeters (mm) × 0.0393701

Tip: You can swap units and convert decimals. Results are rounded for readability.

Examples

Millimeters (mm) Inches (in)
1 mm 0.03937 in
2 mm 0.07874 in
5 mm 0.19685 in
10 mm 0.393701 in
20 mm 0.787402 in
50 mm 1.968505 in
100 mm 3.93701 in
250 mm 9.842525 in
500 mm 19.68505 in
1000 mm 39.3701 in

FAQ

What size is a 10mm socket in inches?

A 10mm socket is extremely close to a 3/8-inch socket (9.5mm), but using the wrong one can strip a bolt.

How much is 25mm of rain?

25mm of rainfall is equal to about 1 inch of rain, which is a significant rainy day.