How Much Do I Need?

Soil Calculator

How much soil do I need?

Enter the size of the bed and how deep you want to fill it. The calculator works out the volume of soil, adds an allowance for settling, and converts it to bags if you enter a bag size.

Units
Bed size

For a raised bed, the depth you plan to fill.

For L-shaped or irregular spaces, split them into rectangles and add each one.

Buying

Loose soil settles once it is watered in. Set to 0 for the exact volume.

Leave blank if you are buying in bulk.

Cost (optional)

Add the price to see an estimated total.

Results update as you type.

Your estimate

Soil to buy

24 bags

1.5 ft³ bags, or 1.5 yd³ in bulk. That covers 1.3 yd³ (35.2 ft³) including 10% extra.

Estimated amount to buy

Bags (1.5 ft³ each)
24 bags
Or in bulk
1.5 yd³
Volume with 10% extra
1.3 yd³ (35.2 ft³)

Calculated quantity (no extra)

Bed area
32 ft²
Cubic yards
1.19 yd³
Cubic feet
32 ft³
Cubic metres
0.906 m³
Litres
906 L
How this was calculated
  1. Area = 8 ft × 4 ft = 32 ft²
  2. Volume = 32 ft² × 12 in deep = 32 ft³ = 1.19 yd³ (27 ft³ per yd³)
  3. With 10% extra = 32 ft³ × 1.1 = 35.2 ft³
  4. Bags = 35.2 ft³ ÷ 1.5 ft³ per bag = 23.47, rounded up to 24
  5. Bulk = 1.31 yd³, rounded up to the next quarter cubic yard = 1.5 yd³
  • Bagged soil is sold by volume, but the fill in a bag can be compacted or fluffed up. The bag count is a guide, not a guarantee.

How the soil calculation works

  1. Area = bed length × bed width.
  2. Volume = area × depth, with everything in the same unit (12 inches = 1 ft; 30 cm = 0.3 m).
  3. Add extra for settling: volume × (1 + extra ÷ 100).
  4. Bags (optional) = volume including extra ÷ bag size, rounded up.

Conversions used: 1 cubic yard = 27 cubic feet ≈ 0.765 m³; 1 cubic foot ≈ 28.3 litres; 1 m³ = 1,000 litres.

Why add extra?

Loose soil and compost contain a lot of air. Once they are watered and walked on, they settle, so a bed filled exactly to the top ends up lower than you planned. The default 10% is a moderate allowance. Increase it for very fluffy mixes or deep beds, or set it to 0 to see the exact geometric volume.

Filling deep raised beds

For very deep beds, some gardeners fill the bottom with other organic material and use bought soil only for the top layer. If you do that, enter only the depth you plan to fill with soil. Many vegetables grow well in 6–12 inches (15–30 cm) of good soil.

Rounding rules

  • Bags are rounded up to a whole bag.
  • Bulk amounts are rounded up to the next 0.25 yd³ (US) or 0.25 m³ (metric). Suppliers set their own minimums, so check before ordering.
  • The calculated volume is shown separately, before the extra and before rounding.