Calculate how much soil you need to fill a garden bed or raised bed.
Equivalent bags
Recommended mix
Usage Tip
Fill a new bed a little proud of the top; fresh soil and compost settle by an inch or two in the first season.
For a raised bed, use the inside dimensions and the fill height.
How much soil do I need for a raised bed?
Multiply the bed length by width by depth to get the volume, then convert to bags or cubic yards. A 4 by 8 ft bed filled 12 in deep needs 32 cubic feet — about 1.2 cubic yards, or 16 of the 2 cubic foot bags. Because soil is sold both ways, this calculator gives the cubic yards, the bag count and the estimated cost, plus a recommended soil mix so you know not just how much, but what to buy.
Raised bed soil depth guide
How deep to fill depends on what you are growing — roots need room. These are good minimums:
| Plants | Soil depth |
|---|---|
| Herbs | 6 to 8 in |
| Leafy greens / flowers | 6 to 12 in |
| Most vegetables | 12 in |
| Root crops (carrots, potatoes) | 12 to 18 in |
| Tomatoes and deep feeders | 18 to 24 in |
Raised bed soil mix guide
Pure topsoil compacts and pure compost stays too wet, so the best beds use a blend. Two popular recipes:
| Mix | Recipe |
|---|---|
| Standard blend | 60% topsoil, 30% compost, 10% peat moss |
| Mel's Mix (square foot gardening) | 1/3 compost, 1/3 peat moss, 1/3 vermiculite |
The calculator splits your total volume into these components so you know how much of each to buy.
Soil volume chart
How far one cubic yard of soil fills a bed depends on depth:
| Depth | One cubic yard covers |
|---|---|
| 3 in | 108 sq ft |
| 6 in | 54 sq ft |
| 12 in | 27 sq ft |
How many bags of soil per cubic yard?
One cubic yard is 27 cubic feet, so it equals 27 of the 1 cubic foot bags, about 18 of the 1.5 cubic foot bags, or roughly 14 of the 2 cubic foot bags. Bulk delivery is usually cheaper once you need more than 10 to 15 bags.
Garden soil calculator
For in-ground garden beds, the same math applies: area times the depth you are amending, divided by 27 for cubic yards. Most in-ground beds only need 3 to 6 in of improved soil or compost worked into the top, far less than filling a deep raised bed from scratch.
Frequently asked questions
How much soil for a 4x8 raised bed?
About 32 cubic feet at 12 in deep, or 1.2 cubic yards — roughly 16 of the 2 cubic foot bags.
How deep should a raised bed be?
At least 12 in for most vegetables, 6 to 8 in for herbs, and 18 in or more for tomatoes and root crops.
What is the best soil mix for raised beds?
A blend of topsoil, compost and an aeration material like peat or vermiculite. Mel's Mix is equal parts compost, peat and vermiculite.
Can I fill a raised bed with just compost?
No. Pure compost holds too much water and settles. Blend it with topsoil and an aeration amendment.
How many bags of soil do I need?
Divide the cubic feet by the bag size. The calculator shows counts for 1, 1.5 and 2 cubic foot bags.
Is bagged or bulk soil cheaper?
Bulk is usually cheaper per yard once you pass 10 to 15 bags, but bagged is easier for one small bed.
Compost Calculator · Mulch Calculator · Gravel Calculator
Coming soon: Topsoil Calculator · Landscape Fabric Calculator
Estimates are for planning. Soil settles and varies in density by source and moisture; buy a little extra for settling and topping up after the first watering, and blend rather than filling beds with a single material. Confirm bulk pricing and delivery minimums with your supplier.