As part of a mix only. Mix 50/50 with compost and add perlite for drainage.

Gardening

Soil Calculator

Calculate how much soil you need for raised beds, pots, and containers. Shows volume in cubic feet, cubic yards, liters, and bags.

Quick Answer

A standard 4×8 foot raised bed at 12 inches deep needs 32 cubic feet of soil, about 1.2 cubic yards or 16 bags of 2 cu ft soil mix.

Container Shape

Length (feet)

Width (feet)

Depth (inches)

Presets:

Results

32.0 ft³

Cubic Feet

1.19 yd³

Cubic Yards

906 L

Liters

Bags Needed

1 cu ft bags

1.5 cu ft bags

2 cu ft bags

3 cu ft bags

About This Tool

The Soil Calculator helps gardeners figure out exactly how much soil, potting mix, or compost to buy for raised beds, pots, and containers. Instead of guessing at the garden center, enter your dimensions and get precise volumes in cubic feet, cubic yards, and the number of bags you need to purchase.

Raised Bed Soil Depth

Most vegetables need at least 6-8 inches of soil depth. Root vegetables like carrots and potatoes need 12 inches or more. The most popular raised bed depth is 12 inches, which accommodates virtually all garden crops. If your bed sits on top of native soil, even 6 inches of quality mix can work since roots will grow down into the ground below.

Bags vs Bulk Delivery

Bagged soil costs more per cubic foot but is convenient for small projects. Bulk delivery (by the cubic yard) is much cheaper for large gardens. One cubic yard equals 27 cubic feet, roughly 13-14 two-cubic-foot bags. If you need more than a cubic yard, bulk delivery usually saves 50-70% compared to bags. Most landscape supply companies deliver in half-yard increments.

Choosing the Right Soil Mix

For raised beds, a popular mix is one-third compost, one-third topsoil, and one-third drainage material (perlite, vermiculite, or coarse sand). Mel Bartholomew's Square Foot Gardening method recommends one-third peat moss (or coco coir), one-third blended compost, and one-third vermiculite. For container gardening, use a soilless potting mix that drains well and doesn't compact.

Soil Settling

Fresh soil mix settles by about 10-20% over the first few months as it compacts and organic matter decomposes. Consider buying 10-15% extra to account for settling, or plan to top off the bed after the first growing season. Mulching the surface also helps reduce settling by protecting the soil structure from rain compaction.

Frequently Asked Questions

How deep should a raised bed be?

12 inches is ideal for most vegetables. Leafy greens and herbs can grow in 6-8 inches. Root vegetables like carrots and parsnips need 12+ inches. If building on top of native soil (not on a patio), even 6 inches works because roots extend into the ground below.

How much does soil cost?

Bagged garden soil costs $4-8 per cubic foot. Bulk delivery runs $25-50 per cubic yard (about $1-2 per cubic foot). Premium raised bed mixes cost more, up to $80-120 per cubic yard delivered. A standard 4x8 bed at 12 inches deep needs about 1.2 cubic yards.

Can I use regular dirt from my yard?

Native soil can work as part of a mix but shouldn't be used alone in raised beds or containers. It often drains poorly, may contain weed seeds and pests, and compacts too much. Mix it 50/50 with compost and amend with perlite for drainage. For containers, always use potting mix.

How much soil settling should I expect?

Fresh soil mix typically settles 10-20% in the first season. Order 10-15% extra or plan to add more soil in fall. Avoid walking on the bed, which increases compaction. Adding mulch on top reduces settling from rain impact. Each year, adding 1-2 inches of compost replenishes volume and nutrients.

What is the best soil mix for raised beds?

A proven mix is one-third topsoil, one-third compost, and one-third aeration material (perlite, vermiculite, or rice hulls). For the Square Foot Gardening method, use equal parts peat moss or coco coir, blended compost from 3-5 sources, and coarse vermiculite. Avoid mixes with too much sand, which adds weight without much benefit.

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