| Grain size | Descriptive terminology | ||
| phi | mm/µm | ||
| −6 to −5 | 32mm - 64 mm | Very coarse | Gravel |
| −5 to −4 | 16 - 32 | coarse | |
| −4 to −3 | 8 - 16 | Medium | |
| −3 to −2 | 4 - 8 | Fine | |
| −2 to −1 | 2 - 4 | Very fine | |
| −1 to 0 | 1 - 2 | Very coarse | Sand |
| 0 - 1 | 500 µm - 1 mm | Coarse | |
| 1 - 2 | 250 µm - 500 µm | Medium | |
| 2 - 3 | 125 - 250 | Fine | |
| 3 - 4 | 63 - 125 | Very fine | |