Raised Bed Soil Calculator
Work out exactly how much soil mix you need to fill a raised garden bed (planter box). Pick a recipe β Mel's Mix, veggie blend, or a custom ratio β and get each ingredient's volume and bag count. Toggle feet/meters and results update live.
Single bed volume = length Γ width Γ depth; total = single Γ quantity.
Each ingredient volume = total Γ its share;
Frequently Asked Questions
What is Mel's Mix?
Mel's Mix is the classic recipe from Square Foot Gardening (by Mel Bartholomew): 1/3 well-rotted compost, 1/3 peat moss (or coco coir), and 1/3 coarse vermiculite. It is light, moisture-holding and fertile, so you rarely need extra fertilizer β the most reliable starting mix for raised beds.
Why is the result in volume, not weight?
Soil ingredients vary a lot in density and moisture, so measuring by volume (cubic feet / liters) is most intuitive and accurate. Bagged soil is sold by volume, so this tool reports bag counts directly to make shopping easy. When filling, simply mound to the rim β no precise weighing needed.
How deep should the soil be?
Most vegetables need 8β12 inches (20β30 cm) of root zone; shallow-rooted leafy greens do fine at 6 inches (15 cm), while deep-rooted crops like tomatoes prefer 12β18 inches (30β45 cm). The default is 12 inches β adjust for your crop.
Can I swap coco coir for peat moss?
Yes. Coco coir (coconut fiber) is a more sustainable, renewable alternative with similar water retention and a more stable pH. Use either in the recipe β the ratio stays the same.