---
description: Channel median sediment size
---

# d50

The table below lists the D50 values of different sediment classes:

| Sediment class | Size \[µm] | Approximate size             |
| -------------- | ---------- | ---------------------------- |
| Boulders       |  > 256,000 |  > Volley ball               |
| Cobbles        |  > 64,000  |  > Tennis ball               |
| Pebbles        |  > 2,000   |  > Match Head                |
| Coarse Sand    |  1,500     |                              |
| Medium Sand    |  375       |                              |
| Fine Sand      |  94        |                              |
| Coarse Silt    |  47        |                              |
| Medium Silt    | 11.7       | Not visible to the human eye |
| Fine Silt      |  4.9       |                              |
| Clay           |  1.95      |                              |
