Rectangular bed: 10 ft × 4 ft, 3 in deep
The 3 inch depth becomes 0.25 ft. The volume is 40 ft² × 0.25 ft.
40 ft² × 0.25 ft = 10 ft³ ÷ 27 = 0.37 yd³
That is 5 bags of 2 ft³ (5 bags before rounding up).
Mulch Calculator
Find out how much mulch you need in cubic yards and bags. Pick the bed shape, enter its size and depth.
Calculator
Enter your dimensions. The result appears here instantly.
How to Calculate Mulch
- Measure the bed. For an odd shape, split it into rectangles and circles and calculate each one.
- Decide the depth you want to spread, in inches or centimeters.
- Choose the matching shape in the calculator and enter the sizes. You can mix feet, inches, yards, mm, cm and m.
- Read the cubic yards for bulk delivery, or the bags for the bag size you will buy.
Mulch Formula
Cubic feet = Area (ft²) × Depth (ft)
Cubic yards = Cubic feet ÷ 27
Bags = Cubic feet ÷ Bag size (ft³), rounded up
Depth must be in feet for this formula, so 3 inches becomes 3 ÷ 12 = 0.25 ft. The calculator converts for you. Bags are rounded up because you cannot buy part of a bag.
How Much Does a Cubic Yard or Bag Cover?
Coverage is volume divided by depth. One cubic yard (27 ft³) and one 2 ft³ bag cover this much at common depths:
| Depth | 1 cubic yard covers | One 2 ft³ bag covers |
|---|---|---|
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
Mulch Examples
Round bed: 8 ft across, 3 in deep
Area of a circle is π × (diameter ÷ 2)², about 50.27 ft² here.
50.2655 ft² × 0.25 ft = 12.57 ft³ ÷ 27 = 0.47 yd³
That is 7 bags of 2 ft³ (6.28 bags before rounding up).
Border around a 12 ft × 8 ft lawn, 2 ft wide, 3 in deep
Pick Rectangle Border and enter the inner size and the border width. The border area is (16 × 12) − (12 × 8) = 96 ft².
96 ft² × 0.25 ft = 24 ft³ ÷ 27 = 0.89 yd³
That is 12 bags of 2 ft³ (12 bags before rounding up).
Adding Extra Mulch
The waste field is optional and starts at 0%. If you want a cushion for settling or uneven ground, enter your own percentage. The result then shows the quantity including that allowance, and bags are counted from the total.
Looking for the plain volume instead? Use the CY Calculator.
Mulch Calculator FAQ
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals 27 bags of 1 ft³, 18 bags of 1.5 ft³, 13.5 bags of 2 ft³, or 9 bags of 3 ft³.
How do I calculate mulch for a round bed?
Choose Circle, measure the diameter, and enter the depth. The calculator uses π × (diameter ÷ 2)² for the area, multiplies by the depth in feet, then divides by 27 for cubic yards.
How deep should mulch be?
Depth depends on the mulch type, the plants and your climate. Many gardeners spread roughly 2 to 3 inches. Check guidance for your plants or your local extension service, and keep mulch from piling against stems and trunks.
Should I add extra for waste?
Mulch settles and spreads unevenly, so some people order a little extra. The optional waste field adds the percentage you choose; it is 0% unless you enter a value.
Is bulk or bagged mulch better?
Bags suit small beds and are easy to carry. Bulk delivery by the cubic yard is often more economical for larger areas. Compare local prices using the optional cost fields, which support price per bag or per cubic yard.