How Much Topsoil for a Raised Bed?
Work out what you need
Measure the area, set the depth, and this converts it to cubic yards, what it weighs on the truck, how many bags that replaces, and roughly what it should cost delivered.
Weight is quoted as a band because moisture moves it more than grade does — topsoil after heavy rain runs to about 125% of its dry weight. The delivered range starts from a published $20–60 per cubic yard and is scaled by how your region's material prices compare with the national average, so treat it as a sanity check and not a quote.
Get a real price from yards near youA standard 4×8 bed filled twelve inches deep takes 1.19 cubic yards. The table below covers every common size.
But before you order that: do not fill a raised bed with pure topsoil. It is the single most common mistake with raised beds, and it is the reason a first-year bed so often underperforms the ground beside it.
Volume by bed size
| Bed | 6 in deep | 12 in | 18 in | 24 in |
|---|---|---|---|---|
| 2×4 (8 sq ft) | 0.15 yd | 0.30 yd | 0.44 yd | 0.59 yd |
| 2×8 (16 sq ft) | 0.30 yd | 0.59 yd | 0.89 yd | 1.19 yd |
| 3×6 (18 sq ft) | 0.33 yd | 0.67 yd | 1.00 yd | 1.33 yd |
| 4×4 (16 sq ft) | 0.30 yd | 0.59 yd | 0.89 yd | 1.19 yd |
| 4×8 (32 sq ft) | 0.59 yd | 1.19 yd | 1.78 yd | 2.37 yd |
| 4×12 (48 sq ft) | 0.89 yd | 1.78 yd | 2.67 yd | 3.56 yd |
For any size not listed, the arithmetic is length × width × depth in inches, divided by 324, which gives cubic yards. The topsoil calculator does it for you, and the coverage chart has the same figures for open ground.
Why pure topsoil fails in a container
Topsoil in the ground is part of a system — worms, roots and freeze-thaw keep it open. Lift the same soil into a box and none of that is happening. It settles, the pore space closes up, and within a season you have a dense block that sheds water off the top and stays wet at the bottom.
The heavier the soil, the faster it happens. A clay-ish topsoil that grows grass perfectly well will set like a brick in a raised bed.
What to fill it with instead
A blend, roughly:
- 50–60% screened topsoil — the mineral body, the nutrient reserve, and what stops the bed drying out in a day
- 30–40% compost — structure and fertility
- 10–20% something coarse — coarse sand, perlite or fine bark, to hold the pore space open
Many yards sell exactly this as a "raised bed mix" or "garden blend," usually for a few dollars more per yard than plain topsoil. It is worth it. If you are blending your own, ask for screened topsoil rather than unscreened — the difference matters more in a bed than it does on a lawn, because you cannot pick stones out of a bed after planting.
Do not use potting mix for the whole volume. It is designed for pots, it is expensive by the yard, and it dries out fast in a large bed — see topsoil vs potting soil.
You do not need to buy the whole depth
Here is the part that saves real money. A 24-inch bed does not need 24 inches of purchased soil. Vegetable roots mostly work the top twelve inches, and even deep-rooted crops rarely need more than eighteen.
If your bed sits on open ground, fill the bottom third with something cheaper:
- Logs, branches and woody prunings. They rot down slowly, hold water, and feed the bed for years. The bed will drop as they break down, so top it up.
- Clean fill or subsoil from elsewhere on the property.
- Leaves and grass clippings layered in, though these settle fast.
On a 4×8 bed at 24 inches, filling the bottom eight inches this way cuts your purchase from 2.37 cubic yards to about 1.58 — a third off the bill.
The exception is a bed on concrete, decking or a membrane. With no drainage below, put a proper drainage layer in and fill the rest with a real mix.
Order about 20% extra
Beds settle hard in the first season — expect to lose two to four inches. Some of that is unavoidable compaction and some is organic matter breaking down, which is the bed working as intended.
Either order 20% over and heap it slightly proud at the start, or plan to top up with compost each spring. Most people end up doing both.
Bags or bulk?
One 4×8 bed at twelve inches is 1.19 yards — about 43 bags at 0.75 cu ft, which is a lot of lifting and roughly $190 in bags against about $110 delivered at a typical $55 fee, if the yard will deliver that little. Two or more beds and bulk wins clearly. Bulk vs bagged has the full break-even.