Raised Bed Soil Calculator

Work out how much soil a raised garden bed needs, how many bags to buy and a simple 60/30/10 mix of topsoil, compost and aeration material.

Soil needed

32 ft³

  • Cubic yards1.19 yd³
  • Bags22 1.5 ft³ bags
  • Topsoil (≈60%)19.2 ft³
  • Compost (≈30%)9.6 ft³
  • Aeration — perlite/pumice (≈10%)3.2 ft³

Estimates only. Round up when you order, and confirm structural details with your local building code.

How to use it

  1. Enter the bed length, width and soil depth.
  2. Enter the number of identical beds.
  3. Pick the bag size you'll buy.

The formula

Cubic feet = length × width × depth × number of beds

Bags = cubic feet ÷ bag size

Worked example

Bed length8 ft
Bed width4 ft
Soil depth12 in
Number of beds1
Bag size1.5 ft³

Result

Soil needed32 ft³
Cubic yards1.19 yd³
Bags22 1.5 ft³ bags
Topsoil (≈60%)19.2 ft³
Compost (≈30%)9.6 ft³
Aeration — perlite/pumice (≈10%)3.2 ft³

Tips before you order

  • Bulk soil is usually cheaper once you need more than about 1 yd³ (27 ft³).
  • Fill tall beds partly with logs or coarse organic material to save soil (hügelkultur style).

Questions

How much soil for a 4×8 raised bed?

A 4 × 8 ft bed filled 12 in deep holds 32 ft³ — about 1.2 yd³ or 22 bags of 1.5 ft³.