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Mulch Calculator
Add your beds and depth to see how much mulch you need in cubic metres, feet and yards — and how many whole bags of your chosen size, or whether bulk is cheaper.
How it's calculated
- Each bed's volume = area × depth (depth converted to metres or feet first).
- Add the beds together and apply your allowance.
- Bags = total volume ÷ bag volume, rounded up to a whole bag.
Worked example
A 100 ft² bed at 3 in deep: 100 × 3 ÷ 12 = 25 ft³ (0.93 yd³). With 2 ft³ bags, 25 ÷ 2 = 12.5, so you need 13 bags before any allowance.
Frequently asked questions
How many bags of mulch do I need?+
Work out the volume — area × depth — and divide by the volume of one bag, then round up. 100 square feet at 3 inches deep is 100 × 0.25 = 25 cubic feet; with 2-cubic-foot bags that's 12.5, so 13 bags.
How deep should mulch be?+
Commonly 5–7.5 cm (2–3 in) for beds, up to 10 cm (4 in) for weed suppression. Keep mulch a few centimetres away from stems and tree trunks.
How big is a bag of mulch?+
It varies by brand and country: 2 and 3 cubic feet are common in the US; 50, 60, 70 and 75 litre bags are common in the UK and Europe. Enter the size printed on the bag you're buying.
Is bulk mulch cheaper than bags?+
Often, for larger jobs. Enter a bag price and a bulk price per cubic metre or yard and the calculator compares them. Remember delivery charges for bulk, which aren't included.
How many cubic feet are in a cubic yard?+
27 (3 × 3 × 3). One cubic metre is about 35.31 cubic feet or 1.31 cubic yards, and 1,000 litres.