About the mulch calculator
Mulch is sold by volume: bulk by the cubic yard (US) or cubic metre, and bagged by the cubic foot or litre. Coverage depends only on area and depth, so once you have measured your beds the calculation is simple — but it is easy to mix up inches and feet. This calculator handles the units and rounds bags up for you.
Horticultural guidance commonly recommends a layer of around 2–4 in (5–10 cm) for most beds, kept clear of plant stems and tree trunks.
How to use it
- Measure each bed. For irregular beds, split them into rectangles and circles or enter the total area.
- Enter the depth you want. Topping up an existing layer usually needs less than a new bed.
- Enter the volume printed on your bags to get a bag count.
- Add bulk or bag prices to compare costs.
Formula
Volume
V = area × depth × (1 + allowance % ÷ 100)Bags
bags = ⌈ V ÷ bag volume ⌉Bags per cubic yard
27 ÷ bag volume in ft³ (13.5 two-cubic-foot bags)- Mulch weight varies enormously with material and moisture, so this calculator works by volume only.
Worked example: A 20 ft × 4 ft bed at 3 in
- Area = 80 ft²; volume = 80 × 0.25 = 20 ft³
- +5 % allowance = 21 ft³ = 0.78 yd³
- 2 ft³ bags: 21 ÷ 2 = 10.5 → 11 bags
Result: About 0.8 yd³ in bulk, or 11 two-cubic-foot bags.
Assumptions and limitations
- Fresh mulch settles and decomposes; the small allowance covers initial settling only.
- Bag volumes are as printed by the manufacturer.
Frequently asked questions
How many bags of mulch are in a yard?
13.5 bags of 2 ft³, 9 bags of 3 ft³, or about 15 bags of 50 L.
How much area does a yard of mulch cover?
At 3 in deep, one cubic yard covers 108 ft²; at 2 in it covers 162 ft².
How deep should mulch be?
Around 2–4 in (5–10 cm) is a widely recommended range. Keep mulch away from stems and trunks to avoid rot.
Is bulk mulch cheaper than bags?
For larger areas bulk delivery is often cheaper per cubic yard, but delivery fees apply. Enter both prices to compare for your job.
Sources and further reading
Results are estimates for planning purposes. See our disclaimer for details.