Mulch & Soil Calculator

Calculate Mulch & Soil

m
m
cm

Volume

0.90 m³

Cubic Yards

1.18

Bags

18

50 L bags

How This Calculation Works

This calculator multiplies the length and width of your garden bed or landscaped area by the desired depth of mulch or soil. The depth is converted from centimetres (or inches) to the same unit as the area dimensions, giving you volume in cubic metres or cubic feet.

The result is also shown in cubic yards (common for bulk delivery) and in bags — using standard bag sizes of 50 litres (metric) or 2 cubic feet (imperial). This helps you decide whether to buy bags from a store or order a bulk delivery from a landscape supplier.

For most garden applications, 5–10 cm (2–4 in) of mulch is ideal. For new raised beds, you may need 15–30 cm (6–12 in) of topsoil or garden mix.

Common Mistakes to Avoid

  • Applying mulch too deep. More than 10 cm (4 in) of mulch can suffocate plant roots and trap excess moisture, leading to rot. For most plants, 5–7.5 cm (2–3 in) is ideal.
  • Piling mulch against tree trunks. "Volcano mulching" — heaping mulch around the base of a tree — promotes bark decay and disease. Keep mulch 10–15 cm (4–6 in) away from trunks.
  • Using the wrong material. Not all mulch is the same. Hardwood mulch is great for flower beds; cedar mulch repels insects; and pine bark acidifies soil (good for azaleas, bad for most vegetables).
  • Forgetting to account for settling. Fresh mulch and loose soil settle by 10–20% over the first few weeks. Consider applying slightly more than your target depth.

Worked Example

Scenario: A garden bed 6 m long × 2 m wide, with 7.5 cm of mulch.

Step 1 — Area: 6 × 2 = 12 m².

Step 2 — Volume: 12 × 0.075 = 0.90 m³.

Step 3 — Cubic yards: 0.90 ÷ 0.7646 = 1.18 yd³.

Step 4 — Bags: 0.90 ÷ 0.05 = 18 bags of 50 L. Buy 18 bags, or order ~1 cubic yard in bulk for better value.

Frequently Asked Questions

How deep should I apply mulch?
For weed suppression and moisture retention, 5–7.5 cm (2–3 in) is ideal. Go up to 10 cm (4 in) for pathways or areas with aggressive weeds. Never exceed 10 cm around plants — it can suffocate roots.
When is it cheaper to buy bulk mulch instead of bags?
Bulk delivery typically becomes more cost-effective when you need more than 2 cubic yards (about 40 bags at 2 ft³ each). A single cubic yard of bulk mulch is often half the price of the equivalent in bags.
How often should I replenish mulch?
Organic mulch (wood chips, bark) breaks down over 1–3 years. Most gardens benefit from a fresh 2.5–5 cm (1–2 in) layer every spring. Inorganic mulch like gravel or rubber lasts much longer.
Can I use mulch in vegetable gardens?
Yes, but choose the right type. Straw, shredded leaves, and compost work well around vegetables. Avoid dyed mulch or fresh wood chips, which can tie up nitrogen as they decompose and starve your plants.