| millimeter | 1 mm | 2 mm | 3 mm | 4 mm | 5 mm | 6 mm | 7 mm | 8 mm | 9 mm | 10 mm | 11 mm | 12 mm | 13 mm | 14 mm | 15 mm | 16 mm | 17 mm | 18 mm | 19 mm | 20 mm | 21 mm | 22 mm | 23 mm | 24 mm | 25 mm | 26 mm | 27 mm | 28 mm | 29 mm | 30 mm | 31 mm | 32 mm | 33 mm | 34 mm | 35 mm | 36 mm | 37 mm | 38 mm | 39 mm | 40 mm | 41 mm | 42 mm | 43 mm | 44 mm | 45 mm | 46 mm | 47 mm | 48 mm | 49 mm | 50 mm | 51 mm | 52 mm | 53 mm | 54 mm | 55 mm | 56 mm | 57 mm | 58 mm | 59 mm | 60 mm | 61 mm | 62 mm | 63 mm | 64 mm | 65 mm | 66 mm | 67 mm | 68 mm | 69 mm | 70 mm | 71 mm | 72 mm | 73 mm | 74 mm | 75 mm | 76 mm | 77 mm | 78 mm | 79 mm | 80 mm | 81 mm | 82 mm | 83 mm | 84 mm | 85 mm | 86 mm | 87 mm | 88 mm | 89 mm | 90 mm | 91 mm | 92 mm | 93 mm | 94 mm | 95 mm | 96 mm | 97 mm | 98 mm | 99 mm | 100 mm |
| metric inch | 2.5 in (metric) | 5 in (metric) | 7.5 in (metric) | 10 in (metric) | 12.5 in (metric) | 15 in (metric) | 17.5 in (metric) | 20 in (metric) | 22.5 in (metric) | 25 in (metric) | 27.5 in (metric) | 30 in (metric) | 32.5 in (metric) | 35 in (metric) | 37.5 in (metric) | 40 in (metric) | 42.5 in (metric) | 45 in (metric) | 47.5 in (metric) | 50 in (metric) | 52.5 in (metric) | 55 in (metric) | 57.5 in (metric) | 60 in (metric) | 62.5 in (metric) | 65 in (metric) | 67.5 in (metric) | 70 in (metric) | 72.5 in (metric) | 75 in (metric) | 77.5 in (metric) | 80 in (metric) | 82.5 in (metric) | 85 in (metric) | 87.5 in (metric) | 90 in (metric) | 92.5 in (metric) | 95 in (metric) | 97.5 in (metric) | 100 in (metric) | 102.5 in (metric) | 105 in (metric) | 107.5 in (metric) | 110 in (metric) | 112.5 in (metric) | 115 in (metric) | 117.5 in (metric) | 120 in (metric) | 122.5 in (metric) | 125 in (metric) | 127.5 in (metric) | 130 in (metric) | 132.5 in (metric) | 135 in (metric) | 137.5 in (metric) | 140 in (metric) | 142.5 in (metric) | 145 in (metric) | 147.5 in (metric) | 150 in (metric) | 152.5 in (metric) | 155 in (metric) | 157.5 in (metric) | 160 in (metric) | 162.5 in (metric) | 165 in (metric) | 167.5 in (metric) | 170 in (metric) | 172.5 in (metric) | 175 in (metric) | 177.5 in (metric) | 180 in (metric) | 182.5 in (metric) | 185 in (metric) | 187.5 in (metric) | 190 in (metric) | 192.5 in (metric) | 195 in (metric) | 197.5 in (metric) | 200 in (metric) | 202.5 in (metric) | 205 in (metric) | 207.5 in (metric) | 210 in (metric) | 212.5 in (metric) | 215 in (metric) | 217.5 in (metric) | 220 in (metric) | 222.5 in (metric) | 225 in (metric) | 227.5 in (metric) | 230 in (metric) | 232.5 in (metric) | 235 in (metric) | 237.5 in (metric) | 240 in (metric) | 242.5 in (metric) | 245 in (metric) | 247.5 in (metric) | 250 in (metric) |
The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore there are thousand millimetres in a metre. There are ten millimetres in a centimetre.
| Name of unit | Symbol | Definition | Relation to SI units | Unit System |
|---|---|---|---|---|
| millimeter | mm | ≡ 1×10-3 m ≡ 0.001 m | ≡ 1×10-3 m ≡ 0.001 m | Metric system SI |
| millimeters | metric inches | millimeters | metric inches |
|---|---|---|---|
| 1 | = 2.5 | 4 | = 10 |
| 1.5 | = 3.75 | 4.5 | = 11.25 |
| 2 | = 5 | 5 | = 12.5 |
| 2.5 | = 6.25 | 5.5 | = 13.75 |
| 3 | = 7.5 | 6 | = 15 |
A metric inch is a nickname for a preferred 1⁄4 subdivision of an ISO 2848 basic module, or 1⁄12 of a metric foot measuring 25 millimetres (0.984 in). A metric inch is 0.4 millimetres (0.016 in) shorter than an inch.
The term was similarly used to refer to the historical Soviet Bloc practice of spacing integrated circuit pins at 1⁄10 of a 25 mm "metric inch" length, instead of the western practice of 1⁄10 of an imperial inch.
| Name of unit | Symbol | Definition | Relation to SI units | Unit System |
|---|---|---|---|---|
| metric inch | in (metric) | = 0.016 in | = 0.0004 m | Metric system SI |
| metric inches | millimeters | metric inches | millimeters |
|---|---|---|---|
| 1 | = 0.4 | 4 | = 1.6 |
| 1.5 | = 0.6 | 4.5 | = 1.8 |
| 2 | = 0.8 | 5 | = 2 |
| 2.5 | = 1 | 5.5 | = 2.2 |
| 3 | = 1.2 | 6 | = 2.4 |
| millimeters | metric inches |
|---|---|
| 1 | = 2.5 |
| 0.4 | = 1 |
| Symbol | Definition |
|---|---|
| ≡ | exactly equal |
| ≈ | approximately equal to |
| = | equal to |
| digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |