Length
Convert millimetre (mm) to inch (in). Length units span pipe diameters (mm, inch), plant dimensions (m, ft), and roughness (µm) — mixing metric and imperial is routine.
1 mm = 0.03937008 in
To convert millimetre to inch, multiply the mm value by 0.03937008. To go the other way, divide by 0.03937008 (or multiply by 25.4).
| mm | in |
|---|---|
| 1 | 0.03937008 |
| 2 | 0.07874016 |
| 5 | 0.1968504 |
| 10 | 0.3937008 |
| 25 | 0.984252 |
| 50 | 1.968504 |
| 100 | 3.937008 |
| 250 | 9.84252 |
| 500 | 19.68504 |
| 1000 | 39.37008 |
Pipe sizes are labelled in inches (NPS) but calculated in mm; equipment layouts mix metres and feet.
Velocity scales with the inverse square of diameter, so a small length error compounds quickly in flow calculations.
Worked example. A length of 100 mm is 3.937008 in.
Multiply the value in mm by 0.03937008 to get in. For example, 10 mm = 0.3937008 in.
1 mm equals 0.03937008 in.
Pipe sizes are labelled in inches (NPS) but calculated in mm; equipment layouts mix metres and feet.