A fresh layer of mulch can change the feel of a garden in an afternoon. Measure the bed, choose the depth you actually need and enter how many beds have those same dimensions.
Refreshing an existing bed? Check what is already there before adding more. Keep tree trunks and plant stems clear rather than piling mulch against them.
How to use this calculator
- Measure each bed at its widest points; for curved beds, break them into rough rectangles and add the results.
- Choose your depth: 2 inches to refresh, 3 inches standard, 4 inches for a new bed.
- Decide bulk versus bags — beyond about 15 to 20 bags, a bulk cubic-yard delivery is usually cheaper.
- Calculate and order slightly over rather than under; a thin patch beside a thick one is very visible.
How mulch volume is calculated
Volume in cubic feet = length × width × (depth in inches ÷ 12) × number of beds. Cubic yards = cubic feet ÷ 27. The bag result assumes 2 cubic feet per bag and rounds up. A cubic yard covers 108 sq ft at 3 inches deep before any allowance. Check the volume stated on the bags or bulk unit you plan to buy.
A 10 ft x 5 ft bed at 3 inches deep needs 12.5 cubic feet of mulch: 0.46 cubic yards, or 7 bags of 2 cu ft once rounded up. The same bed at 4 inches needs about 9 bags.
A few things worth checking
- Ordering by area alone with no depth — 50 sq ft at 2 inches and at 4 inches differ by an entire second load.
- Piling mulch against tree trunks and plant stems (the 'mulch volcano'), which traps moisture and rots bark.
- Forgetting that bagged mulch settles; a bed that looks generous on day one is thinner a month later.
Your questions, answered
How deep should I enter the mulch?
Enter the depth of material you actually intend to add. The 3-inch starting value is a calculator input, not a recommendation for every plant or site. Account for existing material and check a suitable depth for your project.
Is bulk mulch cheaper than bags?
The tool compares quantities, not prices. Use its cubic-yard result for a bulk quote and its bag count for a bagged quote, then include delivery and any minimum-order charges before comparing costs.
How much does a cubic yard of mulch cover?
One cubic yard is 27 cubic feet. Before any allowance, that covers 324 sq ft at 1 inch deep, 162 sq ft at 2 inches, 108 sq ft at 3 inches or 81 sq ft at 4 inches.
What size bags does the calculator use?
The bag result assumes 2 cubic feet per bag and rounds up to a whole bag. If your bag is a different size, divide the cubic-foot volume by the volume stated on that bag and round up instead.
How Deep Should Your Mulch Be?
Give your beds a fresh finish without burying the plants beneath it.