Soil for a 4 × 8 ft raised bed

Raised beds are best measured by the inside length, inside width, and intended fill depth. A garden soil blend may be more appropriate than straight topsoil depending on the plants and drainage. These examples show volume, not a prescribed soil recipe.

How much soil for different fill depths?

Using an interior area of 4 × 8 = 32 sq ft:

Fill depth	Volume	2-cu-ft bags, no extra
6 in	16 cu ft (0.59 yd³)	8
12 in	32 cu ft (1.19 yd³)	16
18 in	48 cu ft (1.78 yd³)	24

At a 12-inch fill depth, adding a 10% allowance changes 32 cu ft to 35.2 cu ft. At 2 cu ft per bag, round 17.6 up to 18 bags. For bulk delivery, 35.2 ÷ 27 ≈ 1.30 cubic yards, before supplier order rounding.

Which depth should you use?

Measure the actual distance from the bed’s inside bottom to the desired soil line, allowing headspace if needed. If the bed is partially filled already, measure the remaining space rather than the full sidewall height.

Topsoil versus raised-bed mix

Bag labels vary: topsoil, compost, potting mix, and raised-bed soil are not necessarily interchangeable. Consider plant needs, local soil, drainage, and whether the bed contacts the ground. Follow the soil supplier’s recommendations instead of assuming pure topsoil is ideal.

Before you buy

Use the stated bag volume, check bulk delivery minimums, and measure internal dimensions. Calculate unusual shapes or multiple beds in the Topsoil Calculator, and convert volumes using Cubic Yard Calculator.

Use your exact measurements

These examples are for planning, not project specifications. Input your own area, product packaging and allowances for a more useful estimate.

Open Topsoil Calculator →

Related tool: Cubic Yard Calculator