| metric inch | 1 in (metric) | 2 in (metric) | 3 in (metric) | 4 in (metric) | 5 in (metric) | 6 in (metric) | 7 in (metric) | 8 in (metric) | 9 in (metric) | 10 in (metric) | 11 in (metric) | 12 in (metric) | 13 in (metric) | 14 in (metric) | 15 in (metric) | 16 in (metric) | 17 in (metric) | 18 in (metric) | 19 in (metric) | 20 in (metric) | 21 in (metric) | 22 in (metric) | 23 in (metric) | 24 in (metric) | 25 in (metric) | 26 in (metric) | 27 in (metric) | 28 in (metric) | 29 in (metric) | 30 in (metric) | 31 in (metric) | 32 in (metric) | 33 in (metric) | 34 in (metric) | 35 in (metric) | 36 in (metric) | 37 in (metric) | 38 in (metric) | 39 in (metric) | 40 in (metric) | 41 in (metric) | 42 in (metric) | 43 in (metric) | 44 in (metric) | 45 in (metric) | 46 in (metric) | 47 in (metric) | 48 in (metric) | 49 in (metric) | 50 in (metric) | 51 in (metric) | 52 in (metric) | 53 in (metric) | 54 in (metric) | 55 in (metric) | 56 in (metric) | 57 in (metric) | 58 in (metric) | 59 in (metric) | 60 in (metric) | 61 in (metric) | 62 in (metric) | 63 in (metric) | 64 in (metric) | 65 in (metric) | 66 in (metric) | 67 in (metric) | 68 in (metric) | 69 in (metric) | 70 in (metric) | 71 in (metric) | 72 in (metric) | 73 in (metric) | 74 in (metric) | 75 in (metric) | 76 in (metric) | 77 in (metric) | 78 in (metric) | 79 in (metric) | 80 in (metric) | 81 in (metric) | 82 in (metric) | 83 in (metric) | 84 in (metric) | 85 in (metric) | 86 in (metric) | 87 in (metric) | 88 in (metric) | 89 in (metric) | 90 in (metric) | 91 in (metric) | 92 in (metric) | 93 in (metric) | 94 in (metric) | 95 in (metric) | 96 in (metric) | 97 in (metric) | 98 in (metric) | 99 in (metric) | 100 in (metric) |
| fermi | 400 000 000 000 fm | 800 000 000 000 fm | 1 200 000 000 000 fm | 1 600 000 000 000 fm | 2 000 000 000 000 fm | 2 400 000 000 000 fm | 2 800 000 000 000 fm | 3 200 000 000 000 fm | 3 600 000 000 000 fm | 4 000 000 000 000 fm | 4 400 000 000 000 fm | 4 800 000 000 000 fm | 5 200 000 000 000 fm | 5 600 000 000 000 fm | 6 000 000 000 000 fm | 6 400 000 000 000 fm | 6 800 000 000 000 fm | 7 200 000 000 000 fm | 7 600 000 000 000 fm | 8 000 000 000 000 fm | 8 400 000 000 000 fm | 8 800 000 000 000 fm | 9 200 000 000 000 fm | 9 600 000 000 000 fm | 10 000 000 000 000 fm | 10 400 000 000 000 fm | 10 800 000 000 000 fm | 11 200 000 000 000 fm | 11 600 000 000 000 fm | 12 000 000 000 000 fm | 12 400 000 000 000 fm | 12 800 000 000 000 fm | 13 200 000 000 000 fm | 13 600 000 000 000 fm | 14 000 000 000 000 fm | 14 400 000 000 000 fm | 14 800 000 000 000 fm | 15 200 000 000 000 fm | 15 600 000 000 000 fm | 16 000 000 000 000 fm | 16 400 000 000 000 fm | 16 800 000 000 000 fm | 17 200 000 000 000 fm | 17 600 000 000 000 fm | 18 000 000 000 000 fm | 18 400 000 000 000 fm | 18 800 000 000 000 fm | 19 200 000 000 000 fm | 19 600 000 000 000 fm | 20 000 000 000 000 fm | 20 400 000 000 000 fm | 20 800 000 000 000 fm | 21 200 000 000 000 fm | 21 600 000 000 000 fm | 22 000 000 000 000 fm | 22 400 000 000 000 fm | 22 800 000 000 000 fm | 23 200 000 000 000 fm | 23 600 000 000 000 fm | 24 000 000 000 000 fm | 24 400 000 000 000 fm | 24 800 000 000 000 fm | 25 200 000 000 000 fm | 25 600 000 000 000 fm | 26 000 000 000 000 fm | 26 400 000 000 000 fm | 26 800 000 000 000 fm | 27 200 000 000 000 fm | 27 600 000 000 000 fm | 28 000 000 000 000 fm | 28 400 000 000 000 fm | 28 800 000 000 000 fm | 29 200 000 000 000 fm | 29 600 000 000 000 fm | 30 000 000 000 000 fm | 30 400 000 000 000 fm | 30 800 000 000 000 fm | 31 200 000 000 000 fm | 31 600 000 000 000 fm | 32 000 000 000 000 fm | 32 400 000 000 000 fm | 32 800 000 000 000 fm | 33 200 000 000 000 fm | 33 600 000 000 000 fm | 34 000 000 000 000 fm | 34 400 000 000 000 fm | 34 800 000 000 000 fm | 35 200 000 000 000 fm | 35 600 000 000 000 fm | 36 000 000 000 000 fm | 36 400 000 000 000 fm | 36 800 000 000 000 fm | 37 200 000 000 000 fm | 37 600 000 000 000 fm | 38 000 000 000 000 fm | 38 400 000 000 000 fm | 38 800 000 000 000 fm | 39 200 000 000 000 fm | 39 600 000 000 000 fm | 40 000 000 000 000 fm |
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 | fermi | metric inches | fermi |
|---|---|---|---|
| 1 | = 400000000000 | 4 | = 1600000000000 |
| 1.5 | = 600000000000 | 4.5 | = 1800000000000 |
| 2 | = 800000000000 | 5 | = 2000000000000 |
| 2.5 | = 1000000000000 | 5.5 | = 2200000000000 |
| 3 | = 1200000000000 | 6 | = 2400000000000 |
The femtometre (American spelling femtometer, symbol fm derived from the Danish and Norwegian word femten, "fifteen"+Ancient Greek: μέτρον, metrοn, "unit of measurement") is an SI unit of length equal to 10−15 metres, which means a quadrillionth of one. This distance can also be called a fermi and was so named in honour of physicist Enrico Fermi, as it is a typical length-scale of nuclear physics.
| Name of unit | Symbol | Definition | Relation to SI units | Unit System |
|---|---|---|---|---|
| fermi | fm | ≡ 1×10−15 m | ≡ 1×10−15 m | Metric system Non-SI |
| fermi | metric inches | fermi | metric inches |
|---|---|---|---|
| 1 | = 2.5E-12 | 4 | = 1.0E-11 |
| 1.5 | = 3.75E-12 | 4.5 | = 1.125E-11 |
| 2 | = 5.0E-12 | 5 | = 1.25E-11 |
| 2.5 | = 6.25E-12 | 5.5 | = 1.375E-11 |
| 3 | = 7.5E-12 | 6 | = 1.5E-11 |
| metric inches | fermi |
|---|---|
| 1 | = 400 000 000 000 |
| 2.5 × 10-12 | = 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 …) |