Topsoil settles, and it is heavy enough that weight decides how it gets delivered. This works out cubic yards and tons, and can split a raised bed fill into a soil and compost blend.
Soil arrives loose and full of air. The first proper watering collapses those voids, and a bed filled level to the rim in the morning can sit an inch low by the following week. That is not material disappearing — it is the same soil occupying less space.
Fifteen per cent is a fair allowance for screened topsoil. A compost-heavy raised bed mix settles more, sometimes a quarter of its loose volume, because organic matter keeps breaking down after it goes in. Expect to top a new raised bed up in its second season regardless.
Suppliers quote topsoil either way, and the two are not interchangeable without knowing the density. Screened dry topsoil runs around 2,000 lb per cubic yard, which is one short ton — a convenient coincidence that only holds while the soil is dry.
Wet soil can be a third heavier. That matters less for the price than for the delivery: a pickup rated for a ton is already over its payload with a single cubic yard of soaked topsoil, whatever the bed will physically hold.
Plain topsoil in a deep raised bed compacts into something closer to a brick than a growing medium. The usual fix is a blend — commonly around 60% topsoil, 30% compost and 10% of something that holds structure, such as perlite, coarse sand or fine bark.
The blend fields above split your total volume into those three components so you can order each separately. The proportions are a starting point, not a rule; drainage-hungry plants want more of the third component, heavy feeders want more compost.
| Assumption | Value used |
|---|---|
| Screened topsoil density | 2000 lb/yd³ |
| Pounds per short ton | 2000 |
| Cubic feet per cubic yard | 27 |
| Bulk order increment | 0.5 yd³ |
| Usable pickup truck load | 2 yd³ |
| Default settling allowance | 15% |
Density is the figure to check locally. It swings with moisture, screening and how much organic matter is in the blend, and a supplier selling by the ton will have their own number. Ask for it before ordering.