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Mulch Calculator
This mulch calculator takes your beds and depth and shows how much mulch you need in cubic meters, 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 meters 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 centimeters 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 liter 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 meter 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 meter is about 35.31 cubic feet or 1.31 cubic yards, and 1,000 liters.
How many bags of mulch are in a cubic yard?+
A cubic yard is 27 cubic feet, so it takes 13.5 two-cubic-foot bags (buy 14) or 9 three-cubic-foot bags exactly.
How much area does a cubic yard of mulch cover?+
27 cubic feet spread 3 inches (0.25 ft) deep covers 27 ÷ 0.25 = 108 sq ft. At 2 inches it covers 162 sq ft and at 4 inches 81 sq ft.
How much mulch do I need per square meter?+
One square meter at 5 cm deep takes 0.05 m³, which is 50 liters; at 7.5 cm it's 75 liters. So a 50-liter bag covers about 1 m² at 5 cm.
Should I add extra mulch for settling?+
Mulch settles and beds are rarely flat, so 5–10% extra is a sensible cushion. The allowance starts at 0% so you see the exact volume first; enter a percentage and the bag count updates.
Can I measure round beds and tree rings?+
Yes. Each bed can be a rectangle, a circle (enter the diameter) or a known area, with its own depth. Add as many beds as you like and the calculator totals them. For a ring around a tree, the trunk is usually small enough to ignore; for a large one, work out the ring's area and use Known area.
Is anything I enter saved or sent?+
No. Everything is calculated in your browser and nothing is uploaded or stored.
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