Raised Bed Soil Calculator

How the Raised Bed Soil Calculator Works

This calculator uses your bed dimensions to compute the exact volume of soil needed in cubic feet and cubic yards. It accounts for rectangular, square, circular and L-shaped beds. Simply enter your bed length, width and depth, and the tool instantly shows you how many bags of soil to buy or how many cubic yards to order for bulk delivery. All calculations run in your browser with no data sent anywhere.

How Much Soil Does a Raised Bed Need?

The amount of soil depends on your bed size and depth. A standard 4x8 foot bed at 12 inches deep needs 32 cubic feet (about 1.2 cubic yards) of soil. Most gardeners fill beds 10-12 inches deep for vegetables, though 6 inches works for herbs and lettuce. For deep-rooted crops like tomatoes and carrots, 18-24 inches is ideal. A 50-50 mix of topsoil and compost gives the best growing results for most vegetables.

Bagged Soil vs Bulk Delivery — Which Saves More?

For small beds under 1 cubic yard, bagged soil from garden centers is convenient and easy to transport. For larger gardens with multiple beds, bulk delivery is significantly cheaper — often 40-60% less per cubic foot. One cubic yard equals about 27 cubic feet, which fills a standard 4x8x1 foot raised bed with soil to spare. Most landscape supply companies deliver bulk soil, compost and garden mix by the cubic yard with a typical minimum order of 1-3 yards.

Best Soil Mix for Raised Beds

The most recommended raised bed mix is 60% topsoil, 30% compost and 10% aeration material like perlite or aged bark. Mel Bartholomew's Square Foot Gardening method recommends equal parts compost, peat moss (or coconut coir) and coarse vermiculite. For vegetable gardens, nutrient-rich compost is essential — it provides organic matter, beneficial microbes and slow-release nutrients that synthetic fertilizers cannot replicate.

Tips for Filling Raised Beds on a Budget

Use the hugelkultur method to reduce soil costs by up to 50%. Place logs, branches and yard debris in the bottom third of deep beds, then layer compost and topsoil on top. The wood decomposes slowly, providing nutrients and retaining moisture for years. You can also use straw bales, cardboard or leaves as filler for the bottom layer of beds deeper than 12 inches. Start composting kitchen scraps now to build your own free soil amendment over time.