CalculatorMulchSoil and compost calculators
Soil is heavier than it looks, settles more than suppliers mention, and only one of these materials belongs in a pot.
Soil amendment calculator
Every gardening book says amend the soil. None of them says with how much.
Compost calculator
There is a ceiling on how much compost soil can take. Most people go straight past it.
Fill dirt calculator
Loose fill and compacted fill are two different volumes. Order the wrong one and the ground sinks.
Potting soil & container calculator
Potting mix is sold in quarts and pots are measured in inches. That mismatch is the whole problem.
Raised bed soil calculator
The mix matters as much as the volume — and one of the three ingredients has a hard ceiling.
Topsoil calculator
Soil is sold by the yard and hauled by the ton. Both numbers matter before you order.
Soil is where volume errors get expensive, because soil is three times heavier than mulch and cannot be carried home a bag at a time past about half a cubic yard. It is also where the material you choose matters as much as the amount: a raised bed filled with pure compost slumps, a container filled with topsoil suffocates, and a hole filled with topsoil sinks for years. These five calculators keep the volume, the weight and the mix straight for each of those jobs.
Frequently asked questions
What is the difference between topsoil, garden soil, compost and potting mix?
Topsoil is screened mineral soil for spreading on the ground. Garden soil is topsoil already blended with organic matter. Compost is an amendment that should stay under about 30 percent of a finished mix. Potting mix contains no soil at all — it is peat or coir and bark, built to stay open in a container. Each has its own calculator here because each has its own density and depth.
Why do the soil calculators add a settling allowance?
Because a freshly spread layer loses volume once it is watered and walked on. Mineral topsoil settles around 10 percent, blended raised bed mixes about 12, and compost-heavy mixes up to 15. Ordering the exact calculated figure is how a new lawn ends up dipped along one edge.
Can I use fill dirt instead of topsoil to save money?
Under the surface, yes, and you should — fill dirt holds a grade because it has no organic matter left to decompose. Cap it with 4 to 6 inches of topsoil for anything you intend to grow in. Using topsoil as structural fill is the expensive way to build a hole that keeps sinking.
How we calculate this
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