Millimeters to Inches Converter

inches = millimeters / 25.4. The factor is exact by definition. A tape measure is marked in sixteenths, so to find the nearest fraction multiply the decimal inches by 16 and round: 0.75 inches x 16 is 12, which is 12/16, or 3/4.

How many inches is 25 mm?

0.9843 inches, which is just under an inch. A 25 mm bolt and a 1 inch bolt are not the same thing, and the 0.4 mm between them is enough to matter in a threaded hole.

What are the common millimeter sizes in inches?

6 mm is about 1/4 inch, 10 mm is about 3/8, 13 mm is about 1/2, 19 mm is about 3/4 and 25 mm is about 1 inch. None of them are exact, which is why a metric socket on an imperial nut rounds the corners off it.

How thick is 12 mm plywood in inches?

0.472 inches, close to 15/32 and usually sold against a 1/2 inch sheet. Metric and imperial plywood are near neighbors at every thickness and identical at none of them, so check before you buy a sheet to match one already in the wall.

Why is 25.4 the number?

It was agreed in 1959 by the US, UK, Canada, Australia, New Zealand and South Africa, who until then each had a slightly different inch. They picked a round figure in millimeters, which is why the inch is now defined from the metric system rather than the other way around.