Raised Garden Bed Soil Calculator

Multiply the bed length by its width and by the fill depth, all in the same unit, to get the volume. For an 8 ft by 4 ft bed filled 12 inches deep, that is 8 times 4 times 1 ft, or 32 cubic feet. This calculator does the math and converts the result into cubic yards, gallons, liters, weight, and the number of bags you need to buy.

Hugelkultur is a method where you pack the bottom of a deep bed with coarse organic material like logs, branches, leaves, and wood chips, then top it with soil. That base layer fills the same footprint as the bed, so it replaces soil one for one by depth. Enter your fill depth and the calculator subtracts that layer, showing how much soil you still need and what percentage you save.

Most vegetables grow well in 8 to 12 inches of soil, and root crops like carrots prefer closer to 12 inches. Beds taller than that are common for easier reach, but you do not need to fill the full height with premium soil. A fill base in the bottom is a cheaper way to take up the extra depth, which is exactly what the fill layer option is for.

Divide the cubic feet by 27, since one cubic yard equals 27 cubic feet. Bulk soil from a landscape yard is sold by the cubic yard, so a 48 cubic foot order is about 1.78 cubic yards. The calculator shows both figures so you can compare buying bags against ordering bulk delivery.

Divide your soil volume by the bag size and round up to the next whole bag. Most US bagged soil comes in 1.5 cubic foot sacks, so 32 cubic feet needs 22 bags. You can change the bag size in the calculator to match the product you plan to buy, and the bag count updates automatically.

Weight is an estimate based on typical loose-fill densities, from about 50 lb per cubic foot for light potting mix to 90 lb per cubic foot for topsoil. Real weight shifts with moisture and how packed the soil is, so treat the figure as a guide for handling and delivery rather than an exact number. Wet soil can weigh noticeably more than the dry estimate.