About this tool
Raised Bed Soil Calculator is a free, in-browser tool that estimates how much soil a raised bed needs and how to split it by mix. Enter each bed's length and width in feet, the fill depth in inches and the number of identical beds, choose a mix, and it returns the total volume in cubic feet and cubic yards plus the volume and bag count for each component. Nothing is uploaded; the math runs on your device.
Total volume in cubic feet = length × width × (depth ÷ 12) × number of beds, and cubic yards = cubic feet ÷ 27. Each component's volume is the total times its share: Mel's Mix splits it into thirds — compost, peat or coir, and vermiculite — while the topsoil-and-compost option uses your compost percentage with the rest as topsoil, and the single-material option puts it all in one. Bags = ceil(component volume ÷ bag size), defaulting to 1.5 cubic feet per bag and always rounded up.
Use it to shop precisely: bagged amendments are sold in cubic feet, and buying by volume avoids the guesswork of guessing at yards. Change the bag size to match the products you find, since compost and potting soil are often sold in 1, 1.5, 2 or 3 cubic-foot bags.