Book 4 · Garden Math

Soil & Mulch Volume

Area × depth, with the depth converted from inches for you — that is the whole calculation, and forgetting the conversion is how people order twelve times too much. Then it prices bags against a bulk load so you can see which actually wins for your quantity.

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How much do you need?

Enter an area and a depth.

Bags or bulk?

Enter both prices to compare.
From the book — Chapter 2. Volume is area × depth, with every dimension in the same unit — so a depth given in inches gets divided by 12 first. A cubic yard is 27 cubic feet, which is why a bulk load goes so much further than a boot full of bags. New beds settle 15–20% over the first season, so overfilling slightly on purpose saves you topping off in spring.

Depth shortcuts: 2 in = ⅙ ft · 3 in = ¼ ft · 4 in = ⅓ ft · 6 in = ½ ft · 8 in = ⅔ ft. 1 cu ft ≈ 7.48 gallons. Everything stays in your browser.