Compost vs Topsoil
Compost and topsoil are both garden materials ordered by volume, and the site’s two calculators share that starting geometry. The Compost Calculator estimates volume, cubic yards, bag count, optional cost and weight for gardens, lawns, and raised beds. The Topsoil Calculator starts from the same area-and-depth volume but adds a user-entered bulk density so it can also report scenario weight and a whole-package count. Each page links to the other as a companion landscape material: the compost page points to the topsoil calculator and the mulch calculator, and the topsoil page points back to the compost and mulch calculators.
What each calculator does
The Compost Calculator computes volume as area times depth, applies the entered waste allowance once, then divides by the entered bag yield and rounds up to whole bags. It can also show cubic yards, bulk cost from an entered bulk price, bag cost from an entered bag price, and weight when a density is entered. The page stresses that bag yield, density, moisture, settling, and delivered volume vary, and that the calculator does not assume a universal density or price.
The Topsoil Calculator computes base volume as area in square feet times depth in inches divided by 12, giving cubic feet. The entered waste percentage scales that volume, and the adjusted volume is displayed in cubic yards using 1 cubic yard equals 27 cubic feet. Scenario weight is adjusted volume times the entered bulk density in pounds per cubic foot, displayed in short tons using 2,000 pounds per ton. Whole packages are rounded up only after the unrounded volume and weight, using the entered package weight in pounds per bag.
Side-by-side comparison
| Feature | Compost Calculator | Topsoil Calculator |
|---|---|---|
| Primary use | Organic amendment for gardens, lawns, raised beds | Building or refreshing planting soil |
| Geometry | Area × depth | Area × depth (ft² × in ÷ 12) |
| Waste allowance | Applied once before bag ceiling | Applied once before weight and package count |
| Bag count | Whole bags from entered yield (volume per bag) | Whole packages from entered pounds per bag |
| Weight | Optional, when density entered | Scenario weight in tons from entered bulk density |
| Cost | Optional bulk or bag price inputs | Not a cost tool |
| Product assumptions | Bag yield, density, moisture entered by user | Density, moisture basis, package weight entered by user |
When to use which
Use the Compost Calculator when the bed needs organic matter — a new raised bed, a garden soil refresh, or a lawn top-dress. Its optional price inputs make it convenient for comparing bagged versus bulk delivery.
Use the Topsoil Calculator when you are establishing or replacing soil volume and need to plan around weight: comparing a bulk delivery quoted by the ton with bagged soil sold by weight, or sanity-checking a truckload. Record the density and moisture basis of the specific product beside the result, because the weight changes with the density you enter.
For either material, measure the bed first with the square footage calculator. If the job is a protective surface cover rather than a soil amendment, the mulch calculator is the companion worksheet.
Where to start
- Compost Calculator — compost volume, cubic yards, bag count, and optional cost and weight.
- Topsoil Calculator — topsoil volume, scenario weight, and whole-package count from entered density and package weight.