The garden bed soil calculator tells you exactly how much soil, compost, or mulch to buy for raised beds. Enter dimensions and get cubic yards, cubic feet, and bag counts. Supports multiple beds and metric units.
How to Calculate Soil for Raised Beds
Getting the soil volume right before buying is critical — delivered bulk soil can't be returned, and making multiple small purchases at garden center prices adds up fast. The formula is simple: Length × Width × Depth in the same units, then convert to cubic yards or bags.
Bagged vs bulk soil
For small beds (under 1 cubic yard), bagged garden soil is convenient. For 1-2 cubic yards, costs are similar. Over 2 cubic yards, bulk delivery from a landscape supplier is typically 40-60% cheaper per cubic foot. A cubic yard of quality garden mix delivered typically costs $35-60 vs $80-120 worth of bagged soil for the same volume.
Soil settling
Fresh garden soil settles 10-20% over the first season as organic matter decomposes and air pockets compress. Fill raised beds slightly above the top edge initially — it will settle to the right level naturally. Budget an extra 10-15% when ordering.
Frequently Asked Questions
How do I calculate cubic yards of soil for a raised bed?
Multiply Length × Width × Depth, all in feet, then divide by 27 to convert cubic feet to cubic yards. For example: 8 ft × 4 ft × 1 ft = 32 cubic feet ÷ 27 = 1.19 cubic yards. This calculator does the math automatically including unit conversions.
How many bags of soil do I need for a raised bed?
Standard bags of garden soil are 1.5 cubic feet. Divide your total cubic feet needed by 1.5 to get bag count. An 8×4 ft bed filled 12 inches deep needs about 32 cubic feet = 21-22 bags. Buying in bulk (by the yard) is cheaper for beds over 2 cubic yards.
What is the best soil mix for raised beds?
The classic Mel's Mix is ⅓ compost, ⅓ peat moss or coco coir, ⅓ coarse vermiculite. For a simpler mix: 60% topsoil, 30% compost, 10% coarse sand or perlite. Avoid 100% potting soil — it dries out too fast and is expensive at raised bed scale.
How deep should raised bed soil be?
6 inches minimum for shallow-rooted plants (lettuce, herbs). 12 inches for most vegetables. 18-24 inches for deep-rooted crops (carrots, potatoes, tomatoes). Most gardeners fill to 12 inches, which is the sweet spot for yield vs. cost.
Is this calculator free?
Yes, completely free with no signup required.