What the calculator estimates
The calculator converts bed length, width, and depth into volume, then applies a waste factor to estimate cubic yards, cubic feet, cubic meters, bags, and cost.
Estimate compost before you order
Enter the bed area and compost depth, and the calculator works out cubic yards, cubic feet, bag counts, and bulk or bagged cost. Coverage changes with moisture, compaction, and amendment ratio, so use this as a planning estimate and confirm with your supplier.
ProjectVegetable bed
Waste factor10%
Bag size1.5 ft³ bags
Bed dimensions
For irregular beds, split the project into rectangles and add them separately.
Bags and cost
Bag size is editable because compost is sold by volume in 1, 1.25, and 1.5 cubic foot bags.
Good depth starting points
Vegetable beds usually get 1 to 2 inches of compost mixed in each season, new beds 2 to 4 inches, raised beds 3 to 6 inches, and lawn topdressing a thin 0.25 inch layer.
Planning note
Compost coverage changes with moisture, compaction, and how much it is blended with soil. Confirm bulk minimums, bag size, and final order before purchase.
Formula used
- Convert length, width, and depth to feet.
- Cubic feet = length x width x depth.
- Cubic yards = cubic feet / 27.
- Cubic meters = cubic feet x 0.0283168466.
- Bags = (cubic feet x waste factor) / bag size in cubic feet, rounded up.
- Bulk cost = cubic yards x waste factor x price per yard.
- Bagged cost = bags x bag price.
How much compost do I need for a garden bed?
Multiply bed length by width by compost depth in feet for cubic feet, then divide by 27 for cubic yards. Add a 10 percent waste factor for settling and spreading. This calculator automates that math for any bed size and depth.
How many cubic feet are in a yard of compost?
One cubic yard equals 27 cubic feet. A standard 1.5 cubic foot bag of compost holds about 0.056 cubic yards, so it takes about 18 bags to make one cubic yard. This calculator lets you set the bag size for your supplier.
How deep should I spread compost?
Mix 1 to 2 inches into vegetable beds each season, build new beds with 2 to 4 inches, fill raised beds 3 to 6 inches deep, and topdress lawns with a thin 0.25 inch layer so you do not smother the grass.
Should I buy compost in bulk or bags?
Bulk compost by the cubic yard is usually cheaper for projects over about 1 to 2 yards. Bags cost more per yard but are easier for small beds, containers, and tight access. This calculator shows both costs so you can compare.
How much waste should I add for compost?
A 10 percent waste factor is common for settling and spreading. Use 15 to 20 percent for very loose or fluffy compost, or for beds with many curves and edges that create more offcuts.
Is this a contractor quote?
No. It is a planning estimate. Prices, delivery fees, taxes, minimum orders, compost blend, and site conditions vary by supplier and location.