How the mulch calculator is calculated
cubic yards = cubic feet ÷ 27
bags = cubic feet ÷ bag size, rounded up
Worked example: 400 square feet at 3 inches
These are the example defaults loaded in the calculator above: a 400 square foot bed, mulched 3 inches deep, in bags of 2 cubic feet.
| Line | Amount |
|---|---|
| 400 sq ft x (3 / 12) | 100 cu ft |
| 100 ÷ 27 | 3.70 cu yd |
| 100 ÷ 2 cu ft per bag | 50 bags |
| One cubic yard covers, at 3 inches | 108 sq ft |
Every default in the calculator is an example so you can see a result straight away. None is a market average. Replace each with your own costs and rates.
How much one cubic yard covers
A cubic yard is 27 cubic feet. Spread 3 inches deep, which is a quarter of a foot, it covers 108 square feet. At 2 inches it covers 162 square feet, and at 4 inches it covers 81. These match the coverage figures in a landscaping supplier guide read on 11 Nov 2026 (LawnStarter's mulch calculator guide), and they follow from the volume formula above.
Bags or bulk
Bags are easy to carry and buy in small amounts. Bulk is delivered in cubic yards and is often cheaper per cubic foot on a large job, but a delivery charge and a pile on the driveway come with it. A cubic yard holds 13.5 bags of 2 cubic feet. Enter both prices and the calculator shows which costs less for your area.
Depth is your call
The depth you spread depends on the bed, the material and your reason for mulching. The calculator takes any depth from the 2 to 4 inch buttons or whatever you type. A thinner layer covers more area. Whatever you choose, measure the bed itself, not the lawn around it.
Turn this into an estimate or invoice
The button under the result carries the mulch into the document generator as a line with its quantity and price. To price the whole landscaping job with labor and a markup, open the cost estimator set up for landscaping. For designs and presets, see the landscaper invoice page.
Related calculators
- Cubic yard calculatorYards from any length, width and depth
- Gravel calculatorCubic yards and tons of stone
- Square footage calculatorAdd up the area of beds and rooms
- Landscaping price calculatorPrice a whole landscaping job
Questions people ask
How much mulch do I need for 400 square feet?
At 3 inches deep you need 100 cubic feet, which is 3.70 cubic yards. At 2 inches you need about 2.47 cubic yards, and at 4 inches about 4.94.
How many bags are in a cubic yard?
A cubic yard is 27 cubic feet, so it holds 13.5 bags of 2 cubic feet, 18 bags of 1.5 cubic feet, or 27 bags of 1 cubic foot.
How deep should mulch be?
That depends on the bed and the material, so follow the advice for what you are growing. The calculator works for any depth you enter, and shows how much area one cubic yard covers at that depth.
Is bulk mulch cheaper than bags?
Often per cubic foot on a large area, but a delivery fee can change that. Enter both prices in the calculator to compare the totals for your bed.
How do I measure an irregular bed?
Break it into rectangles and triangles, work out each area, and add them. The square footage calculator adds rectangles for you.