4×8 Raised Bed Soil Calculator
How much soil for a 4×8 raised bed? Pick a mix to get the total volume and a per-component shopping list.
A 4×8 raised bed has a 32 sq ft footprint. Filled to the common 10-inch depth, it holds about 0.99 cubic yards of soil — the calculator above is already set to 8 × 4 ft, so pick a mix and read off the shopping list.
The footprint is fixed at 8 × 4 ft, so fill depth is the one number worth thinking about. Shallow-rooted crops like lettuce and herbs get by on 6–8 inches; tomatoes, squash, and root vegetables want closer to 10–12 inches of loose mix to spread into.
A balanced, beginner-friendly mix. Good default for most vegetable beds.
Total soil needed
0.99cu yd
26.7 cu ft · buy ~29.3 cu ft to allow for settling
| Component | Volume | Bags |
|---|---|---|
| Topsoil | 16 cu ft | 11 × 1.5 cu ft |
| Compost | 8 cu ft | 8 × 1 cu ft |
| Aeration (perlite or vermiculite) | 2.7 cu ft | 2 × 2 cu ft |
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4×8 soil volume by fill depth
Volume scales directly with depth on a fixed footprint — double the depth and you double the soil. At 10 inches, a 4×8 bed takes 0.99 cubic yards. Here's every standard depth for this exact size, with bag counts for the three most common bag sizes.
| Fill depth | Cubic feet | Cubic yards | 1 cu ft bags | 1.5 cu ft bags | 2 cu ft bags |
|---|---|---|---|---|---|
| 6 in | 16 cu ft | 0.59 cu yd | 16 bags | 11 bags | 8 bags |
| 8 in | 21.3 cu ft | 0.79 cu yd | 22 bags | 15 bags | 11 bags |
| 10 in | 26.7 cu ft | 0.99 cu yd | 27 bags | 18 bags | 14 bags |
| 12 in | 32 cu ft | 1.19 cu yd | 32 bags | 22 bags | 16 bags |
Bottom line: a 4×8 bed at 10 in needs 0.99 cu yd — scale from there for a different depth.
Shopping list for one 4×8 bed
Using the default 60% topsoil / 30% compost / 10% aeration blend at 10 inches deep, here's how the total splits by component and how many bags of each to buy.
| Component | Volume | Bags to buy |
|---|---|---|
| Topsoil | 16 cu ft | 11 bags (1.5 cu ft) |
| Compost | 8 cu ft | 8 bags (1 cu ft) |
| Aeration (perlite or vermiculite) | 2.7 cu ft | 2 bags (2 cu ft) |
Bottom line: buy bags in these ratios, or switch to Mel's Mix or a custom blend in the calculator above.
Filling more than one 4×8 bed
Building several 4×8 beds at once? Multiply the single-bed volume by the bed count — the calculator's "number of beds" field does this for you. Totals below already include the ~10% settle buffer, since fresh mix compacts after its first watering.
| Number of beds | Total volume | Buy (with settle buffer) |
|---|---|---|
| 1 | 0.99 cu yd | 29.3 cu ft |
| 2 | 1.98 cu yd | 58.7 cu ft |
| 3 | 2.96 cu yd | 88 cu ft |
| 4 | 3.95 cu yd | 117.3 cu ft |
How it's calculated
- 1
Enter bed size
Length, width, and fill height in inches, plus how many beds. Heights of 6–12 inches are typical.
- 2
Pick a mix recipe
The default blend is 60% topsoil, 30% compost, 10% aeration. Mel's Mix is equal parts compost, peat/coir, and vermiculite.
- 3
Get a shopping list
We split the total volume by the recipe and show bags of each component, plus a ~10% settle buffer.
Frequently asked questions
How much soil for a 4×8 raised bed?
A 4×8 bed at 10 inches deep holds about 26.7 cubic feet — roughly 1 cubic yard. The calculator breaks that into bags of topsoil, compost, and aeration.
What soil mix is best for raised beds?
A balanced default is 60% topsoil, 30% compost, 10% aeration (perlite or vermiculite). Square-foot gardeners often use Mel's Mix — equal parts compost, peat/coir, and vermiculite.
Can I fill the bottom with something cheaper?
Yes. For deep beds, the bottom 6–12 inches can be coarse fill (logs and branches — hügelkultur — or cheap fill dirt). Only the top ~10–12 inches needs real growing mix.