Compost Calculator
Estimate compost volume, bag quantity, bulk weight, settling allowance and bagged-versus-bulk cost for garden beds.
Default project preview
1.36 yd³
Compost bags
19
Base volume
1.23 yd³
Bed area
200 ft²
Bulk weight
1,467 lb
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Bed length
Enter this project assumption in ft. The current imperial default is 20 ft.
Bed width
Enter this project assumption in ft. The current imperial default is 10 ft.
Compost depth
Enter this project assumption in in. The current imperial default is 2 in.
Equal garden beds
Enter this project assumption in a unitless value. The current imperial default is 1. Minimum: 1.
Settling and extra allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Volume per bag
Enter this project assumption in ft³. The current imperial default is 2 ft³.
Bulk density
Enter this project assumption in lb/ft³. The current imperial default is 40 lb/ft³.
Bulk price
Enter this project assumption in per yd³. The current imperial default is 55 per yd³. Minimum: 0.
Price per bag
Enter this project assumption in a unitless value. The current imperial default is 6. Minimum: 0.
How to read the outputs
Compost bags
2 ft³ each. Default preview: 19.
Base volume
before allowance. Default preview: 1.23 yd³.
Bed area
all beds. Default preview: 200 ft².
Bulk weight
entered density. Default preview: 1,467 lb.
Bulk cost
entered volume rate. Default preview: $74.69.
Bagged cost
rounded full bags. Default preview: $114.00.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Volume = bed length × width × depth × bed count. Settling allowance is applied before converting to bulk units or dividing by bag volume.
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 30, 2026
Use this calculator to estimate compost volume and delivery quantities from treatment area, application depth, waste allowance and supplier unit size. It supports soil-amendment ordering, not a prescription for application depth.
Calculation steps
- 1Measure the treatment area.
- 2Convert compost depth to feet or metres.
- 3Multiply area × depth to obtain volume.
- 4Add allowance and convert to bags, cubic yards or cubic metres.
Worked numerical example
Applying 2 inches of compost over 1,000 ft² requires 166.7 ft³, or about 6.17 yd³. With 10% allowance, plan for about 6.8 yd³ and round to the supplier’s delivery increment.
Purchasing and rounding
Bulk compost is ordered by supplier volume increments; bagged compost is rounded to whole bags using the printed bag volume.
Interpret the result
Depth has a direct linear effect: doubling depth doubles volume. Settling and blending can change the apparent finished depth.
Page-specific assumptions
- Uniform application depth.
- Area is measured horizontally.
- Supplier volume is accurate.
- No major existing grade changes.
Common mistakes
- Entering inches as feet.
- Confusing cubic feet with cubic yards.
- Using a universal application depth.
- Ignoring delivery minimums.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
FAQ
Compost Calculator questions
How deep should compost be applied?+
The right depth depends on whether compost is top-dressed, incorporated or used in a new bed. More is not always better.
Why can compost weight vary so much?+
Moisture, feedstock, particle size and decomposition level strongly affect bulk density.
Is compost the same as topsoil?+
No. Compost is organic amendment, while topsoil is mineral soil. Many projects use them differently or in a blend.