Metric to Inches Converter
Enter any metric length in mm, cm, or meters and get inches using the exact definition 1 in = 25.4 mm. Also shows feet + inches and the nearest tape-measure sixteenth.
Example: with Measurement 100 · Metric unit Centimeters (cm) → Inches: 39.37 in.
Computed by the calculator below using its default values. Change any input to see your own numbers.
📐 Work both units with a dual-scale rule
Check it outThe metric to inch conversion, with examples
Since 1959 the inch has been defined as exactly 25.4 mm, so every metric to inches conversion is one exact division: inches = mm ÷ 25.4. Worked examples: 50 mm = 1.97 in, 100 cm = 39.37 in, and 2 m = 78.74 in, which reads more naturally as 6 ft 6.74 in.
Handy anchors make mental metric-to-inch conversion quick: 25.4 mm is 1 inch, 30 cm is just under a foot (11.81 in), and a meter is about 39.37 in — roughly 1.09 yards, why a meter stick beats a yardstick by almost 4 inches. For shop work, the tool also rounds to the nearest 1/16 in: an 18 mm socket is 0.71 in, which lands on the 11/16 mark (0.6875 in) of a US tape.
How it’s calculated
Inches = millimeters ÷ 25.4, the exact definition of the inch since the 1959 international yard and pound agreement; centimeters are multiplied by 10 and meters by 1,000 to reach millimeters first. Feet + inches takes whole feet as floor(inches ÷ 12) with the remainder in inches. The fraction row rounds to the nearest 1/16 in and reduces (10/16 → 5/8), so it is approximate by up to 1/32 in.
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Common mistakes
- Multiplying by 25.4 instead of dividing — 100 mm is 3.94 in, not 2,540 in.
- Mixing up cm and mm for a silent 10× error: 50 mm is 1.97 in, but 50 cm is 19.69 in.
- Rounding a meter to 39 in when cutting — the missing 0.37 in (nearly 1 cm) is enough to ruin a fit.
Frequently asked questions
What is the metric to inches formula?
Inches = millimeters ÷ 25.4. Equivalently, multiply centimeters by 0.3937 or meters by 39.3701.
How many inches is 1 cm?
1 cm = 0.3937 in, a little under half an inch. Ten centimeters is 3.94 inches.
Is 25.4 mm exactly one inch?
Yes. The inch has been defined as exactly 25.4 mm by international agreement since 1959, so the conversion carries no rounding at all.
How do I convert metric to feet and inches?
Convert to inches first, then split by 12. For 2 m: 2,000 ÷ 25.4 = 78.74 in = 6 ft 6.74 in.
What metric wrench matches a 1/2 inch bolt?
1/2 in is exactly 12.7 mm, so a 13 mm wrench is the closest metric size and usually fits with slight play.