Raised Bed Soil Calculator
Enter the dimensions of each raised bed to find out how much soil you need — in cubic feet, cubic yards, and bag counts.
Last updated
Planning where to put your beds? Use our land area calculator to measure your available yard space on a map first.
Your Results
Volume needed
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Cubic feet
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1 cu ft bags
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2 cu ft bags
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How We Calculate
Formula, assumptions, and sources
Inputs you provide
- Dimensions of each bed — length, width, and depth (add as many beds as you need; the calculator totals them)
Formula
For each bed: cubic feet = length (ft) × width (ft) × depth (in) ÷ 12. Metric uses cubic meters = length (m) × width (m) × depth (cm) ÷ 100.
Totals across beds are summed, then divided by 27 to give cubic yards (imperial).
Bag counts = total cubic feet ÷ bag size, rounded up. Both 1 cu ft and 2 cu ft counts are shown because both sizes are common at US retailers.
Assumptions
- Default depth of 12 inches (30 cm) is a middle-of-the-road depth for vegetable beds. Shallow-rooted crops can manage with 6–8 inches; deep-rooted crops (carrots, tomatoes) prefer 18–24 inches.
- The calculator assumes the bed is filled to the specified depth with soil from the bottom up. If you're using a fill layer underneath (logs, branches, cardboard, gravel) you only need to calculate the top soil layer.
- Bag sizes of 1 cu ft and 2 cu ft are the standard retail sizes for raised-bed soil, garden soil, and most bagged soil blends at US garden centers.
Sources
- Bed-depth recommendations for common vegetables align with guidance from US university extension services — see our raised-bed soil mix guide for the full breakdown.
Limitations
- Soil settles after filling, often by 10–15% in the first season. Order a little extra or plan to top off after the first watering.
- This calculator sizes volume, not a specific mix. If you're buying individual ingredients to make your own blend (topsoil + compost + vermiculite, or a Mel's Mix ratio), use the total cubic feet from this calculator as the base and allocate by the recipe.
- Fill methods like hugelkultur — layering logs, branches, or other bulk filler under the soil — reduce the amount of soil needed. Subtract the volume of the fill layer from your total before ordering.
Frequently Asked Questions
How much soil do I need to fill a raised bed?
Multiply the length × width × depth (all in feet) to get cubic feet, then divide by 27 for cubic yards. A standard 4×8 ft bed at 12 inches deep needs 32 cubic feet — about 1.19 cubic yards or 16 bags of 2 cu ft soil.
How deep should a raised bed be?
Most vegetables do well with 12 inches of soil depth. Shallow-rooted crops like lettuce and herbs can manage with 6–8 inches. Deep-rooted vegetables such as carrots, tomatoes, and squash prefer 18–24 inches.
How many bags of soil do I need for a raised bed?
It depends on bed size and bag size. For a 4×8 ft bed at 12 inches deep (32 cu ft), you would need 32 bags of 1 cu ft soil or 16 bags of 2 cu ft soil. The calculator above gives you exact counts for your specific beds.
What is the best soil mix for raised beds?
A popular starting point is “Mel’s Mix”: equal parts compost, peat moss or coconut coir, and coarse vermiculite. Pre-blended raised bed mixes are also available and save time. Avoid using native garden soil alone — it compacts and drains poorly in raised beds.
Can I use potting soil in a raised bed?
You can, but it is not ideal for large beds — potting soil is expensive at volume, designed for containers, and dries out quickly. Purpose-made raised bed soil or a blended mix is generally better value and performance for raised garden beds.