Measurement conversion tool

Convert ruler measurements between inches, cm, and mm

Use this converter when a ruler reading needs to move between inch fractions, decimal inches, centimeters, and millimeters. For actual-size screen measurement, calibrate the ruler before measuring.

Live conversion

1 in = 2.54 cm = 25.4 mm.

Conversion rules

Use millimeters when you need the finest common ruler unit.

Use centimeters for quick metric readings; 1 cm equals 10 mm.

Use inch fractions when matching hardware, fabric, and US product dimensions.

Convert before rounding when accuracy matters.

Common ruler fractions

These are the fraction marks most often found on inch rulers. Use the millimeter equivalent when you need to match a metric drawing or product spec.

Fractional inch Decimal inch Millimeters
1/16 in 0.0625 in 1.5875 mm
1/8 in 0.125 in 3.175 mm
3/16 in 0.1875 in 4.7625 mm
1/4 in 0.25 in 6.35 mm
5/16 in 0.3125 in 7.9375 mm
3/8 in 0.375 in 9.525 mm
7/16 in 0.4375 in 11.1125 mm
1/2 in 0.5 in 12.7 mm
5/8 in 0.625 in 15.875 mm
3/4 in 0.75 in 19.05 mm
7/8 in 0.875 in 22.225 mm
1 in 1 in 25.4 mm

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