Garden Soil Calculator

Topsoil is screened mineral soil sold for filling and levelling. Garden soil is topsoil already blended with compost and often fertiliser, formulated for planting. Use topsoil for volume and garden soil for the top 6 to 8 inches where roots grow — filling a deep bed entirely with bagged garden soil is expensive and unnecessary.

Twenty-seven 1 cubic foot bags, 18 of the 1.5 cubic foot size, or about 13 or 14 two-cubic-foot bags. Once you need more than roughly a yard, bulk delivery is dramatically cheaper.

Six to eight inches suits annuals, vegetables and most perennials. Shrubs and deep-rooted plants want 12 inches or more. If you are building over existing soil rather than filling a container, you can count the decent soil already there toward that depth.

Measure the length and width in feet at the widest points and multiply them. For an irregular bed, break it into rectangles, circles and triangles, calculate each one separately and add the results together. Rounding up slightly is safer than rounding down.

Bulk is almost always cheaper per cubic yard once you need more than about 1 cubic yard — roughly 27 bags. Bags win when you need a small amount, have nowhere to dump a pile, or want to spread the job over several weekends.

A half-ton pickup can usually carry about 1 cubic yard of light material like mulch, but only around half a cubic yard of wet soil or gravel because of the weight. Check the weight figure above against your vehicle's payload rating before you load up.