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How Much Soil Do I Need for a Raised Bed?

It's the most common question new raised-bed gardeners ask: how much soil do I actually need? The answer depends on three dimensions — length, width, and depth — and the shape of y…

All Shapes Supported Inches, Feet, CM & Meters Bag Count & Cost Estimate

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Enter your raised bed dimensions below

Bed Shape
Measurement Units
Bag Size & Cost Options Optional

How Much Soil Do I Need for a Raised Bed?

It's the most common question new raised-bed gardeners ask: how much soil do I actually need? The answer depends on three dimensions — length, width, and depth — and the shape of your bed. A 4×8 bed at 12 inches deep needs 32 cubic feet. A 4×4 at 12 inches needs 16 cubic feet. Use the calculator above to get the exact figure for your specific bed, along with the number of bags to buy.

How to Use This Calculator

Select your bed shape (Rectangle, Square, or Circle), choose your unit of measurement, then enter your dimensions. For rectangular and square beds, enter length, width, and depth. For circular beds, enter the diameter and depth. Click Calculate Soil Needed to see your results instantly in cubic feet, cubic yards, liters, and gallons — plus bag counts for all four standard bag sizes.

Understanding Your Results

Cubic feet is the unit printed on most bagged soil at garden centers. Use this number to count bags. Cubic yards is the unit used by landscape bulk suppliers — divide cubic feet by 27 to get cubic yards. Liters is the metric equivalent (1 cu ft = 28.32 liters). Gallons is helpful for smaller container calculations (1 cu ft = 7.48 gallons).

Volume Formula (Rectangle)
Volume = Length × Width × Depth (all in feet)

Soil Mix Recommendation

The best all-purpose raised bed mix is 60% quality topsoil, 30% compost, and 10% perlite or coarse sand. This blend drains well, retains moisture, and provides the nutrients plants need. Avoid filling raised beds with pure topsoil — it compacts and restricts root growth. Always include at least 25–30% organic matter.

💡 Order 10% extra: Soil settles 10–15% after the first thorough watering. Buying a little extra prevents a second trip to the store.
Common Questions

Frequently Asked Questions

A 4×8 foot raised bed at the standard 12-inch depth requires 32 cubic feet of soil — about 1.19 cubic yards. You would need 32 one-cubic-foot bags or 16 two-cubic-foot bags. At an 18-inch depth you need 48 cubic feet, and at 24 inches you need 64 cubic feet. Use the calculator above to adjust for your specific depth.
A 4×4 foot raised bed at 12 inches deep holds 16 cubic feet of soil. You will need 16 one-cubic-foot bags or 8 two-cubic-foot bags. Buy one or two extra bags to account for settling after the first watering.
The most versatile depth is 12 inches, which suits most vegetables and flowers. For deep-rooted plants like tomatoes and carrots, 18–24 inches is better. For shallow-rooted herbs and lettuce, 6–8 inches is enough. When in doubt, build to 12 inches — it is the best all-purpose choice.
Divide cubic feet by 27 to get cubic yards (since 1 yard = 3 feet, and 3³ = 27). For example: 54 cubic feet ÷ 27 = 2 cubic yards. The calculator above always shows both units simultaneously, so you never need to do this math manually.
For irregular shapes, break the bed into simple geometric sections (rectangles or triangles), calculate the volume of each section separately using this calculator, and add the totals together. For circles, select the Circle tab above and enter the diameter and depth. Most raised beds are rectangular — the Rectangle tab handles those perfectly.
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