Millimetres to Inches Converter

Convert millimetres to inches or inches to millimetres. Clean, quick and accurate.

Rounding

Presets

Conversion factor 1 inch = 25.4 mm (exact)

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How it works

The inch is defined as exactly 25.4 millimetres. To convert millimetres to inches, divide by 25.4. To convert inches to millimetres, multiply by 25.4.

in = mm ÷ 25.4
mm = in × 25.4

When this helps

DIY, woodworking and machining
Electronics and PCB footprints
Product specs that flip between metric and imperial

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