How to use this calculator
- Enter or choose area to cover.
- Enter or choose area in.
- Enter or choose depth.
- Enter or choose depth in.
- Enter or choose bulk density (optional).
- The compost needed updates as you type. Use Copy result or Share to keep it.
Method
Volume = Area × Depth; Weight = Volume × Bulk density; Bags = Volume in litres ÷ Bag size, rounded up
- Area
- converted to m²
- Depth
- converted to m
- 1 yd³
- 0.764555 m³
Worked example
- Volume = 100 m² × 0.05 m = 5 m³ (6.54 yd³).
- Weight = 5 × 600 kg = 3 t; bags = 5000 L ÷ 50 L = 100.
Covering 100 m² with 5 cm of compost takes 5 m³, about 3 tonnes or 100 bags of 50 L.
What the result means
Order a little extra: compost settles after spreading, and loose deliveries are measured before settling.
Assumptions and limits
- Even depth over the whole area.
- Weight depends heavily on moisture; treat the tonnage as approximate.
Questions
How deep should compost be?
It depends on the use; a few centimetres as a topdressing, more when building new beds. Follow local guidance for your soil and crop.
How many 50 L bags make a cubic metre?
Twenty, because a cubic metre is 1,000 litres.