Raised Bed Soil Calculator
Calculate total cubic feet, cubic yards, and component blend ratios for garden raised beds.
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How to Calculate Soil for Raised Beds
Calculating volume for rectangular raised beds requires converting depth from inches into feet:
Cubic Feet = Length (ft) × Width (ft) × (Depth (inches) / 12) × Number of Beds
Cubic Yards = Cubic Feet / 27
Mel's Mix Formula: Popularized by Square Foot Gardening, this blend calls for 1/3 blended compost (for organic nutrients), 1/3 peat moss or coconut coir (for moisture retention), and 1/3 coarse horticultural vermiculite (for aeration and root expansion). It never compacts and requires zero fertilizer in year one.
Frequently Asked Questions
How many cubic feet of soil are in an 8x4 raised bed?
An 8x4 ft bed that is 12 inches deep requires exactly 32 cubic feet of soil (1.19 cubic yards). If filled with 1.5 cu ft bags, you will need 22 bags.
Does soil settle in a raised bed?
Yes. Freshly mixed organic soil settles by approximately 10% to 15% after the first few deep waterings. Plan on filling the bed nearly flush to the rim.
Can I fill a tall 24-inch waist-high bed with logs and branches?
Yes. The Hügelkultur method fills the bottom 12 inches with logs, fallen branches, and dried leaves, requiring 50% less expensive soil mix while rotting over time into sponge-like organic humus.