Mulch Calculator
Enter the size of your garden bed and mulch depth in millimetres to get cubic metres, litres and the number of 56.6 L bags – and whether bulk is cheaper.
Formulas shown on this page · Last reviewed October 2026
How the mulch calculator works
volume (m³) = area (m²) × depth (mm) ÷ 1,000
litres = volume × 1,000
bags = litres × (1 + waste) ÷ bag size (L)
For a circular bed or tree ring, the area is π × (diameter ÷ 2)². One cubic metre is 1,000 litres, so a 56.6 L bag covers about 0.75 m² at 75 mm deep.
How deep should mulch be?
| Use | Depth |
|---|---|
| Flower beds and borders | 50–75 mm |
| Around shrubs and trees | 75–100 mm |
| Vegetable garden (fine mulch) | 50 mm |
| Weed suppression on paths | 75–100 mm |
Buying mulch in Canada
Popular choices include cedar, hemlock and dyed or natural hardwood mulch. Home centres sell 56.6 L (2 cu ft) bags, while landscape yards sell bulk mulch by the cubic yard, so yards are shown too. A layer applied in spring after the ground has warmed keeps weeds down; in autumn mulch also insulates roots against freeze–thaw cycles.
At the default prices, bagged mulch costs about $106 per cubic metre ($6.00 per 56.6 L bag) compared with roughly $55 per m³ in bulk before delivery. Bulk wins for beds over about 1 m³. These are typical prices – check your local supplier.
Frequently asked questions
How much mulch do I need for a 6 × 2 m bed at 75 mm deep?
The base volume is 0.9 m³ (900 L). With 5% extra, order 0.95 m³ – about 945 L.
How many 56.6 L bags is that?
945 L ÷ 56.6 L = 17 bags (rounded up), costing about $102 versus $52 in bulk.
How many cubic yards of mulch is that?
One cubic yard is 0.765 m³, so 0.95 m³ is about 1.24 yd³. A 56.6 L bag is 2 cu ft.
Should I keep mulch away from trunks and stems?
Yes. Leave a small gap around trunks and plant stems so moisture does not sit against the bark and cause rot.