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Raised Bed Soil Calculator

A raised bed soil calculator works out how much soil it takes to fill a raised garden bed — in cubic feet, cubic yards and bags — for one bed or several. Enter the bed size and fill depth and it does the volume.

Your measurements

Result

Raised beds eat more soil than people expect (a single 8 × 4 ft bed a foot deep is over a cubic yard), so this stops the mid-project run for more bags.

How it is calculated

Volume = length × width × depth per bed, times the number of beds, in cubic feet and cubic yards. Bag count assumes 1.5 ft³ bags. Bulk (by the cubic yard) is far cheaper once you're past about a cubic yard.

Steps

Enter the bed length, width and fill depth.
Enter how many identical beds you're filling.
Read the cubic feet, cubic yards and bag count.
Mix roughly 60% soil, 30% compost, 10% aeration.
Fill to about an inch below the rim and top up after watering.

Worked example

One 8 × 4 ft bed filled 12 in deep needs about 32 cubic feet of soil — roughly 1.2 cubic yards, or 22 bags of 1.5 ft³.

Common questions

How much soil for a raised bed?

Length × width × depth. An 8 × 4 ft bed a foot deep is about 32 cubic feet (1.2 cubic yards). The calculator does any size and multiple beds.

Bags or bulk soil?

Bulk delivery is much cheaper beyond about a cubic yard; bags suit one small bed.

What soil mix for raised beds?

Roughly 60% topsoil or garden soil, 30% compost, 10% aeration like perlite or coarse sand.

Do I fill the whole depth with soil?

You can part-fill deep beds with coarse material at the very bottom, but most roots want at least 10-12 in of good soil.