Mulch Calculator
Work out how much mulch your beds need at the depth you want, in cubic yards for a bulk delivery or in bags if you are carrying it home yourself.
Switching units keeps your measurements. Nothing is reset.
Areas
Depth
How deep you want the finished layer of mulch.
How are you buying it?
Waste allowance
10% covers uneven beds and the settling that happens in the first weeks.
Offcuts, breakages, pattern matching and the occasional damaged piece all mean you use more material than the bare area. Keeping a few spare pieces for future repairs is also normal.
This is a planning allowance, not a rule. Adjust it for your layout, your material and your own tolerance for a second trip to the store.
Estimated cost
Cost uses the price you enter. This product never shows invented market prices.
Your result appears here
Enter your measurements to see how much material to buy.
How to use this calculator
- 1
Measure each bed. Curved borders are easier as a rectangle plus a circle or triangle than as one awkward shape.
- 2
Set the depth you want once the mulch has settled, in the inches box.
- 3
Choose bulk for a delivered load, or bags and enter the volume printed on the bag. Two cubic feet is common, but it is worth checking.
- 4
Adjust the overage if your beds are uneven or you are topping up an existing layer rather than starting bare.
A worked example
A 30 ft × 10 ft bed at 3 in deep, bought in 2 ft³ bags with a 10% overage:
Measured volume
75 ft³75 ft³
Add the waste allowance
75 ft³ × 1.182.5 ft³
Divide by the coverage of one package
82.5 ft³ ÷ 2 ft³41.25
Round up to whole packages
round up 41.2542
Coverage you are buying
42 × 2 ft³84 ft³
You will need
42 bags
This example is produced by running the calculator above, so it always matches what the tool does.
The formula
Volume is area × depth. The overage is applied to that volume, and the total is divided by the volume of one bag, then rounded up, because part bags cannot be bought. One cubic yard is 27 cubic feet, which is why a yard of mulch is roughly thirteen and a half of the common two cubic foot bags.
Mulching well
Deeper is not always better
Mulch piled against stems and trunks holds moisture where the plant does not want it. Keep it clear of the base, and let the depth you choose be about weed suppression and moisture, not about using up the delivery.
Topping up needs less than starting fresh
If last year is still partly there, measure the depth you need to add rather than the total depth you want. Entering the full depth over an existing layer will roughly double the order.
Bulk is cheaper, bags are easier
A cubic yard replaces around thirteen or fourteen bags. Bulk is usually far cheaper per unit, but it arrives in a pile on the drive and has to be moved that day.
Common questions
- How many bags of mulch are in a cubic yard?
- A cubic yard is 27 cubic feet, so it is thirteen and a half of the common two cubic foot bags, or fourteen once you round up. Check the volume on your bags: three cubic foot bags are also sold.
- How deep should mulch be?
- That depends on the plants, the climate and whether you are suppressing weeds or retaining moisture. This calculator does not assume a depth for you, because the right answer varies too much to put in a formula.
- Does mulch settle?
- Yes, noticeably in the first weeks, which is what the overage allowance covers. Bark and wood chips settle more than compost.