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Raised bed soil mix calculator

Choose a recipe from an extension service or enter your own mix, and see how many cubic feet and bags of each ingredient your bed takes.

Example split

32cubic feet in total

32 cubic feet in total (1.19 cubic yards)

  • Topsoil 66.7% · 21.33 ft³ · 15 bags of 1.5 ft³
  • Compost 33.3% · 10.67 ft³ · 8 bags of 1.5 ft³
IngredientShareCubic feetCubic yardsBags
Topsoil66.7%21.330.7915 of 1.5 ft³
Compost33.3%10.670.48 of 1.5 ft³

Bags are rounded up for each ingredient separately. Mixed ingredients can settle into slightly less space than their separate volumes.

Example: a 4 × 8 ft bed filled 12 inches deep. Replace it with your bed.

Your bed, measured inside the walls

The upper end of “2/3 to 1/2 topsoil and 1/2 to 1/3 plant-based compost”.

Ingredients

The recipes

Each preset is a mix an extension service or the Square Foot Gardening Foundation publishes. Where the body gives a range, the note says which end the preset uses.

RecipePublished byParts
Two-thirds topsoil, one-third compostUniversity of Minnesota ExtensionTopsoil 67%, Compost 33%
Equal parts compost and topsoilUniversity of Maryland ExtensionTopsoil 50%, Compost 50%
70% topsoil, 30% compostIowa State University ExtensionTopsoil 70%, Compost 30%
Equal parts topsoil, organic matter and coarse sandIowa State University ExtensionTopsoil 33%, Compost or other organic matter 33%, Coarse sand 33%
Equal parts compost, drainage material and soilUtah State University ExtensionCompost 33%, Coarse sand, vermiculite, pumice or perlite 33%, Native soil or topsoil 33%
On paving: equal parts compost and soilless mixUniversity of Maryland ExtensionCompost 50%, Soilless growing mix 50%
Mel’s Mix: peat, vermiculite and blended compostSquare Foot Gardening FoundationPeat 33%, Vermiculite 33%, Blended compost 33%

Measure the fill first

Use the inside length and width of the bed and the soil depth you plan, not the wall height. For several beds or a round or tapered one, work out the total in the raised bed soil calculator and enter it as the total volume.