Mulch Calculator Square Feet: Accurate Area & Depth Estimates
Know your garden bed square footage? Use this calculator to work out exact mulch volume in cubic feet, litres, and bags based on your target depth.
MULCH ESTIMATOR
FREEHow much do you need?
YOUR ESTIMATE
1.1 m³1,100 litres including 10% extra
Area20 m²
60L bags19
Est. cost£161.5
We round bags up so you are not caught short. Base quantity before allowance: 1,000 litres.
The Square Foot to Mulch Formula
To find the volume of mulch required for any square footage, multiply your area by the depth in inches, then divide by 12 to convert inches into feet:
SQUARE FEET TO CUBIC FEET FORMULA
Cubic Feet = (Square Feet × Depth in Inches) ÷ 12
To convert cubic feet into UK Litres, multiply by 28.32. To convert into Cubic Yards, divide by 27.
Common Bed Example (100 Sq Ft at 3 Inches Depth):
- 100 sq ft × 3 inches = 300.
- 300 ÷ 12 = 25 cubic feet.
- In litres: 25 × 28.32 = 708 Litres.
- In standard 50-litre bags: 708 ÷ 50 = 14.2 bags (order 16 bags with buffer).
Square Foot Coverage per Mulch Depth Chart
This chart shows how many square feet 1 cubic yard (765 litres) and standard UK bags will cover at different depths:
| Desired Depth | 1 Cubic Yard Covers | 1 Bulk Bag (850L) Covers | 1 × 70L Bag Covers | 1 × 50L Bag Covers |
|---|---|---|---|---|
| 1 inch (2.5 cm) | 324 sq ft (30.1 m²) | 360 sq ft (33.5 m²) | 29.7 sq ft (2.8 m²) | 21.2 sq ft (2.0 m²) |
| 2 inches (5.0 cm) | 162 sq ft (15.1 m²) | 180 sq ft (16.7 m²) | 14.8 sq ft (1.4 m²) | 10.6 sq ft (1.0 m²) |
| 3 inches (7.5 cm) | 108 sq ft (10.0 m²) | 120 sq ft (11.1 m²) | 9.9 sq ft (0.92 m²) | 7.1 sq ft (0.66 m²) |
| 4 inches (10.0 cm) | 81 sq ft (7.5 m²) | 90 sq ft (8.4 m²) | 7.4 sq ft (0.69 m²) | 5.3 sq ft (0.49 m²) |
| 6 inches (15.0 cm) | 54 sq ft (5.0 m²) | 60 sq ft (5.6 m²) | 4.9 sq ft (0.46 m²) | 3.5 sq ft (0.33 m²) |
Selecting the Best Depth for Your Square Footage
- 2 Inches (5 cm): The ideal thickness for annual vegetable beds, herbaceous flower borders, and flower beds with established shrubs. Provides adequate moisture retention while letting irrigation reach root systems.
- 3 Inches (7.5 cm): The gold standard for weed suppression on bare soil borders, foundation plantings, and tree basins. Retards over 85% of annual seed germination.
- 4 Inches (10 cm): Excellent for woodland pathways, heavily weed-infested borders, or exposed windy slopes where lighter wood chips might shift.
- 6+ Inches (15 cm): Safety depth required under swing sets, climbing frames, and playground equipment to meet British safety standard BS EN 1177.