Mulch Needed Calculator

Working out mulch is a volume problem. Multiply the bed area by the depth you plan to spread, then convert that volume into the bags or yards the supplier actually sells.

Bed lengthThe length of the bed, in feet.Bed widthThe width of the bed, in feet.Mulch depthHow deep the mulch layer should be, in inches.Bag sizeThe volume of one bag, in cubic feet. Two is the usual size.Price per bagLeave at zero to hide the cost figure.

Mulch needed in cubic feet

Bags to buy: 25
Equivalent in cubic yards: 1.8519
Total cost: 150

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

cubic feet = length x width x (depth in inches / 12)

L, W: The length and width of the bed, in feet
d: The depth of mulch, in inches
V: The volume of mulch needed, in cubic feet
B: The number of bags, rounded up to whole bags

How to check the result by hand

1
Measure the bed
Length times width gives the area in square feet. A 20 by 10 foot bed is 200 square feet.
2
Convert the depth to feet
Three inches divided by twelve is 0.25 feet. Forgetting this step multiplies the answer by twelve.
3
Multiply area by depth
200 times 0.25 is 50 cubic feet, which is the volume of mulch the job needs.
4
Divide by the bag size
Fifty cubic feet in bags of two is 25 bags exactly. Any remainder rounds up, because part bags are not sold.
5
Check the bulk equivalent
Fifty cubic feet is 1.85 cubic yards, so a bulk order of two yards is the one that covers the job.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Mulch Needed page.