Raised Bed Soil Calculator
From bed dimensions to bags of soil. Measure the inside, add only the depth you need, and plan your purchase.
Your soil estimate
PLAN · FILL · GROWA little measuring.
A better estimate.
Add the inside length, width and soil depth to see your volume and bag count.
- Cubic feet
- Cubic yards
- Liters
- Cubic meters
For rectangular, flat-bottomed beds with a uniform soil layer. Volume is an estimate. Bag counts round up once for all beds together. Bulk suppliers may have minimum orders.
Enter your bed dimensions to begin.
How much soil do I need for a raised bed?
Measure the inside length and width of your rectangular bed. Then measure the soil depth you want to add. Multiply these dimensions in consistent units, then multiply by the number of identical beds.
The outside frame includes material that soil will not occupy. Use the clear space inside it. For beds with different dimensions, calculate each size separately and combine the volumes before ordering.
The formula, made visible.
US: ft³ = length (ft) × width (ft) × depth (in) ÷ 12 × beds
Metric: L = length (cm) × width (cm) × depth (cm) ÷ 1,000 × beds
Purchase volume = base volume × (1 + extra allowance ÷ 100)
Bags = purchase volume ÷ bag volume, rounded up
An 8 × 4 ft bed filled 12 in deep needs 32 ft³ (906.139 L). With no allowance and 2 ft³ bags, buy 16 bags.
A 120 × 60 cm bed with 30 cm of soil needs 216 L. At 50 L per bag, buy 5 bags. Adding 10% gives 237.6 L, still 5 bags.
Cubic feet vs. cubic yards
27 ft³ = 1 yd³. Divide cubic feet by 27 when comparing a bulk order. The 32 ft³ example is about 1.185 yd³. One cubic foot equals 28.316846592 L, and 1 m³ equals 1,000 L.
A few questions, before you fill.
How many bags of soil should I buy?
Divide the total soil volume by the volume printed on your bag, using the same units, and round up to a whole bag. This soil bag calculator combines identical beds before rounding: three beds needing 30 L each require two 50 L bags, not three.
What if the bed already contains soil?
Enter only the depth you still need to add. Existing soil, logs, filler or a false bottom occupy space. This calculator assumes the remaining layer is uniform across a flat rectangular bed.
Does this include settling?
Not by default. Extra allowance starts at 0%. You can choose up to 30% if appropriate for your material and filling method. There is no single settling percentage that fits every mix, and the calculator does not predict it.
Can I use this for different bed sizes?
Calculate each size separately and add the volumes. The number-of-beds field is for identical beds only. To avoid buying unnecessary bags, round up after combining the volumes you plan to purchase together.
Can I convert the result to weight?
Not without knowing the material’s density and moisture. This calculator gives volume only, not kilograms or pounds, soil recipes, delivery prices or planting-depth recommendations.
Method & privacy
For rectangular, flat-bottomed beds with a uniform soil layer. Results use full calculation precision; displayed volumes round to at most three decimals. Positive volumes below 0.001 show <0.001. A very small tolerance removes machine rounding noise at whole-bag boundaries.
All calculations happen in your browser. Dimensions are not saved, added to links or sent to our servers. Only your site appearance preference is remembered. Your measurements and chosen allowance determine the estimate; check them before buying.
Covering several garden surfaces? Use the Mulch Calculator to combine different areas under one shared depth.