# Compost Volume Calculator

> Work out how much compost or mulch you need to cover an area to a given depth, in m³, cubic yards, litres, tonnes and bags.

Category: Agriculture · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/compost-volume-calculator

Compost needed is area × depth. Enter the bulk density of your material to convert the volume to weight.

Also called: Mulch calculator, Compost coverage calculator.

## Inputs
- Area to cover (default 100)
- Area in (options: Square metres, Square feet, Acres, Hectares; default m2)
- Depth (default 5)
- Depth in (options: cm, inches; default cm)
- Bulk density (optional) (unit kg/m³; default 600; optional)
- Bag size (optional) (unit L; default 50; optional)

## Results
- Compost needed
- Compost needed
- Compost needed
- Compost needed
- Approximate weight
- Bags to buy

## Formula

```
Volume = Area × Depth;  Weight = Volume × Bulk density;  Bags = Volume in litres ÷ Bag size, rounded up
```

Where:
- Area: converted to m²
- Depth: converted to m
- 1 yd³: 0.764555 m³

## Worked example
1. Volume = 100 m² × 0.05 m = 5 m³ (6.54 yd³).
2. Weight = 5 × 600 kg = 3 t; bags = 5000 L ÷ 50 L = 100.

**Result:** 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.

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- [Concrete Calculator](https://calculators.geekmidst.com/calculators/concrete-calculator)
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Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/compost-volume-calculator