The raised bed fill cost calculator calculates exactly how much soil you need and what it will cost, whether you're using Mel's Mix, topsoil blend, or custom materials. Supports metric and imperial.
Bed Dimensions
Fill Estimate
Enter bed dimensions to calculate.
How to Calculate Raised Bed Soil Volume
Filling a raised bed is one of the biggest costs of setting up a new vegetable garden. Calculating the volume precisely prevents over-buying expensive bagged soil or under-buying and having to make a second store run.
The Volume Formula
Volume = length × width × depth. For a 4×8×12" bed: 4 × 8 × 1 = 32 cubic feet. Convert to cubic yards for bulk delivery: 32 / 27 = 1.19 cubic yards. Most bulk soil deliveries have minimums of 1-2 cubic yards, and bulk pricing is significantly cheaper than bags for anything over 0.5 cubic yards.
Choosing Fill Material
Mel's Mix is the premium choice — weed-free, nutrient-rich, and excellent drainage. However, it costs $150-250+ to fill a 4×8×12" bed. A topsoil blend is more economical ($60-120) but may contain weed seeds. Consider a compromise: topsoil blend as the base (bottom 6 inches) with Mel's Mix or premium compost on top where roots grow.
Soil Settlement
Fresh soil settles 10-20% in the first few months as it compacts and organic matter breaks down. Fill beds slightly above the top board initially — the soil will settle to the correct level by the end of the first season. Add a 1-2 inch top-dressing of compost each year to maintain volume and fertility.
FAQ
Is this raised bed fill calculator free?
Yes, completely free with no signup required. Material cost estimates are based on typical retail prices — your local prices may vary.
How much soil do I need for a 4x8 raised bed?
A 4×8 foot bed filled to 12 inches deep needs 32 cubic feet (1.19 cubic yards) of soil mix. At 6 inches deep, you need 16 cubic feet. For Mel's Mix, that's roughly 10.7 cubic feet each of vermiculite, peat moss, and blended compost for a 12-inch deep 4×8 bed.
What is Mel's Mix for raised beds?
Mel's Mix (from square foot gardening pioneer Mel Bartholomew) is: 1/3 vermiculite, 1/3 peat moss or coconut coir, and 1/3 blended compost (from multiple sources). This mix is lightweight, retains moisture well, and is essentially weed-free. It costs more than topsoil initially but eliminates tilling and produces excellent yields.
What is the best depth for a raised bed?
6 inches is the minimum for most vegetables. 12 inches is ideal and the most common choice — it accommodates deep-rooted vegetables like carrots, parsnips, and tomatoes. 18 inches provides extra growing depth for potatoes and allows better root development for perennials. Never go below 6 inches for vegetables.
How many cubic feet are in a bag of garden soil?
Most bagged garden soil is sold in 1 cubic foot or 2 cubic foot bags. Some premium mixes (like potting mix or Mel's Mix components) come in 8-quart bags — there are 8 quarts in 0.29 cubic feet, so you need about 3.5 of those 8-qt bags per cubic foot. Calculate cubic feet needed first, then buy bags accordingly.