Soil Amendment Calculator

About this calculator

Adding compost, aged manure, or another soil amendment to a garden bed only helps if it is applied at an adequate depth across the whole bed — too shallow and it barely mixes into the root zone, too deep wastes material and money. Amendment volume is a simple area-times-depth calculation, but it needs a unit conversion because garden area is measured in square feet and amendments are typically sold by the cubic yard.

This calculator takes your bed's area and your target amendment depth and converts the result into cubic yards, the unit most bulk compost and soil yards use for pricing and delivery — so you can order the right quantity without over- or under-buying for the season's beds.