How to use it
Type the inches in the Inches box: a decimal such as 2.75, a fraction such as 5/8, or both such as 3 1/2. The answer is the length in millimeters to four decimal places. The Metric mm box rounds it to a tenth of a millimeter.
For feet and inches, type in the Feet-inch box the way you would write it: 2' 6". To go from millimeters to inches, type in the Metric mm box, or use the mm to inches converter.
The math
- Inches to millimeters: multiply by 25.4. 3 1/2 inches is 3.5 × 25.4 = 88.9 mm.
- A fraction to millimeters: divide the top number by the bottom, then multiply by 25.4. 5/8 is 0.625, and 0.625 × 25.4 = 15.875 mm.
- Feet and inches to millimeters: turn it into inches first. 2' 6" is 2 × 12 + 6 = 30 inches, and 30 × 25.4 = 762 mm.
One inch is exactly 25.4 mm by definition, so any sixteenth of an inch comes out exact to four places. An odd 32nd or 64th needs five or six places; the answer rounds it to four and marks it with ≈.
Fractions of an inch in mm
Every 32nd of an inch up to 1 inch.
| Fraction | Decimal inches | Millimeters |
|---|---|---|
| 1/32" | 0.03125 in | 0.7938 mm |
| 1/16" | 0.0625 in | 1.5875 mm |
| 3/32" | 0.09375 in | 2.3813 mm |
| 1/8" | 0.125 in | 3.175 mm |
| 5/32" | 0.15625 in | 3.9688 mm |
| 3/16" | 0.1875 in | 4.7625 mm |
| 7/32" | 0.21875 in | 5.5563 mm |
| 1/4" | 0.25 in | 6.35 mm |
| 9/32" | 0.28125 in | 7.1438 mm |
| 5/16" | 0.3125 in | 7.9375 mm |
| 11/32" | 0.34375 in | 8.7313 mm |
| 3/8" | 0.375 in | 9.525 mm |
| 13/32" | 0.40625 in | 10.3188 mm |
| 7/16" | 0.4375 in | 11.1125 mm |
| 15/32" | 0.46875 in | 11.9063 mm |
| 1/2" | 0.5 in | 12.7 mm |
| 17/32" | 0.53125 in | 13.4938 mm |
| 9/16" | 0.5625 in | 14.2875 mm |
| 19/32" | 0.59375 in | 15.0813 mm |
| 5/8" | 0.625 in | 15.875 mm |
| 21/32" | 0.65625 in | 16.6688 mm |
| 11/16" | 0.6875 in | 17.4625 mm |
| 23/32" | 0.71875 in | 18.2563 mm |
| 3/4" | 0.75 in | 19.05 mm |
| 25/32" | 0.78125 in | 19.8438 mm |
| 13/16" | 0.8125 in | 20.6375 mm |
| 27/32" | 0.84375 in | 21.4313 mm |
| 7/8" | 0.875 in | 22.225 mm |
| 29/32" | 0.90625 in | 23.0188 mm |
| 15/16" | 0.9375 in | 23.8125 mm |
| 31/32" | 0.96875 in | 24.6063 mm |
| 1" | 1 in | 25.4 mm |
Inches to mm chart, 1 to 24 inches
| Inches | Millimeters | Centimeters |
|---|---|---|
| 1" | 25.4 mm | 2.54 cm |
| 2" | 50.8 mm | 5.08 cm |
| 3" | 76.2 mm | 7.62 cm |
| 4" | 101.6 mm | 10.16 cm |
| 5" | 127 mm | 12.7 cm |
| 6" | 152.4 mm | 15.24 cm |
| 7" | 177.8 mm | 17.78 cm |
| 8" | 203.2 mm | 20.32 cm |
| 9" | 228.6 mm | 22.86 cm |
| 10" | 254 mm | 25.4 cm |
| 11" | 279.4 mm | 27.94 cm |
| 12" | 304.8 mm | 30.48 cm |
| 13" | 330.2 mm | 33.02 cm |
| 14" | 355.6 mm | 35.56 cm |
| 15" | 381 mm | 38.1 cm |
| 16" | 406.4 mm | 40.64 cm |
| 17" | 431.8 mm | 43.18 cm |
| 18" | 457.2 mm | 45.72 cm |
| 19" | 482.6 mm | 48.26 cm |
| 20" | 508 mm | 50.8 cm |
| 21" | 533.4 mm | 53.34 cm |
| 22" | 558.8 mm | 55.88 cm |
| 23" | 584.2 mm | 58.42 cm |
| 24" | 609.6 mm | 60.96 cm |
Feet to mm
| Feet | Millimeters | Meters |
|---|---|---|
| 1' 0" | 304.8 mm | 0.3048 m |
| 2' 0" | 609.6 mm | 0.6096 m |
| 3' 0" | 914.4 mm | 0.9144 m |
| 4' 0" | 1,219.2 mm | 1.2192 m |
| 5' 0" | 1,524 mm | 1.524 m |
| 6' 0" | 1,828.8 mm | 1.8288 m |
| 8' 0" | 2,438.4 mm | 2.4384 m |
| 10' 0" | 3,048 mm | 3.048 m |
| 12' 0" | 3,657.6 mm | 3.6576 m |
| 16' 0" | 4,876.8 mm | 4.8768 m |
| 20' 0" | 6,096 mm | 6.096 m |
Questions
How do I convert inches to mm?
Multiply the inches by 25.4. 2 inches is 50.8 mm and 3 1/2 inches is 88.9 mm.
How many mm is 1/4 inch?
1/4 inch is exactly 6.35 mm, because 0.25 × 25.4 = 6.35.
How many mm is 1/2 inch?
1/2 inch is exactly 12.7 mm.
How many mm is 5/8 inch?
5/8 inch is exactly 15.875 mm, a little under 16 mm.
How many mm is a foot?
A foot is 12 inches, so it is 12 × 25.4 = 304.8 mm, or 0.3048 m.
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