Mulch Calculator
Calculate mulch bags and cubic yards for your garden bed, then compare bagged and bulk costs.
How to calculate mulch
Measure each bed and choose the intended mulch depth. Multiply the area by the depth to get a volume, then divide by the volume in each bag.
Bags = cubic feet needed ÷ cubic feet per bag, rounded up
A 20 ft × 10 ft bed at 3 inches deep needs 50 cubic feet, or about 1.85 cubic yards. That fills exactly 25 bags of 2 cubic feet. With a 10% allowance, you need 55 cubic feet, so buy 28 bags.
How much area does a bag of mulch cover?
At 3 inches deep, a 2-cubic-foot bag covers 8 square feet; a 3-cubic-foot bag covers 12 square feet. Divide bag volume in cubic feet by depth in feet. These figures assume an even layer and exclude extra material.
Topping up an existing mulch layer
When adding mulch, enter the additional depth you need, not the combined depth of old and new material. For example, adding 1 inch across a 200 sq ft bed requires 200 ÷ 12 = 16.67 cubic feet, or 9 whole bags of 2 cubic feet before allowance. Measure the remaining layer in several places. The 1-inch addition is a calculation example, not a recommended depth for every bed.
Compare bagged and bulk mulch prices
For the 55-cubic-foot order above, 28 two-cubic-foot bags at an example $4 each cost $112. Bulk mulch at an example $40 per cubic yard costs 55 ÷ 27 × $40 = $81.48. The calculator shows both options when you enter both prices.
That $30.52 difference is for material only. Compare delivery charges and minimum order sizes before choosing. The mulch bag conversion guide covers other bag sizes and coverage depths.
Bagged cost uses the whole bag count. Bulk cost uses the unrounded volume, so a supplier’s minimum order or delivery increment can change the quote.
Filling a raised bed? Use the soil calculator to subtract an existing layer and compare bags with bulk soil.
Unit reference: NIST volume conversion factors.
Common questions
How many 2-cubic-foot bags make a cubic yard?
One cubic yard is 27 cubic feet, equivalent to 13.5 bags of 2 cubic feet. You would need 14 whole bags to cover at least one cubic yard.
Can I use litre bags?
Yes. Select litres and enter the volume printed on the bag. One cubic metre equals 1,000 litres, so it needs 20 bags of 50 litres before allowance. Use bag volume rather than the weight in kilograms.
How do I calculate an irregular garden bed?
Split it into rectangles and circles or approximate sections. Calculate each section separately and add the volumes before rounding the final bag order.
Questions about a result? See how our calculators are built or report a calculation issue.