18 millimeters to inches
0.71 in
18 mm = 0.71 in.
inches
0.71in
18 mm = 0.71 in
In short
How many inches is 18 millimeters?
18 mm = 0.71 in. 1 millimeter = 0.039370 inches, so the working is 18 × 0.039370 = 0.71.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 millimeter = 0.039370 inches 18 × 0.039370 = 0.71
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (in) | Off by |
|---|---|---|
| Whole number | 1 | +0.29134 |
| 1 decimal | 0.7 | −0.00866 |
| 2 decimals | 0.71 | +0.00134 |
Round trip: take 0.71 in back the other way and you land on 18.0340 mm — a drift of 0.0340 mm. That gap is the rounding, not the conversion.
Frequently asked questions
What is 18 millimeters in inches?
18 millimeters is 0.71 inches. 1 millimeter = 0.039370 inches, so the working is 18 × 0.039370 = 0.71.
How accurate is 0.71 in?
Rounding to 0.71 in and converting straight back gives 18.0340 mm, a drift of 0.0340 mm from the 18 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
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