Raised Bed Soil Calculator
Find the missing fill volume in a rectangular raised bed, then convert it to bulk volume or whole bags from the label.
- New fill depth
- 12 in
- Net soil volume
- 32 ft³ (1.19 yd³)
- Order volume
- 35.2 ft³ (1.3 yd³)
- Whole bags
- 18
- Topsoil share (50%)
- 17.6 ft³ (0.65 yd³)
- Compost share (30%)
- 10.56 ft³ (0.39 yd³)
- Other share (20%)
- 7.04 ft³ (0.26 yd³)
This calculates fill volume, not a horticultural soil recipe. Set blend percentages from your own plan.
Show calculation
8 ft × 4 ft × (12 − 0) in ÷ 12 × (1 + 10%)Transparent method and editable product assumptions. Verify current labels and project requirements.
How this calculator works
Measure the inside dimensions of the bed rather than the outer frame. Subtract the average depth of settled material already present from the target fill depth.
The remaining rectangular volume is reported in cubic feet and cubic yards or cubic meters. A settling or handling allowance is applied once before package rounding.
Bag count uses the filled volume printed on the package, not bag weight. If you plan a blend, calculate the total volume here and multiply it by your own recipe percentages; the tool does not recommend horticultural proportions.
Formula
New soil = inside length × inside width × (target depth − existing depth); bags = ceil(new soil × (1 + extra) ÷ bag volume)The live substitution appears with your result.Control example: 8 × 4 ft bed
A 12-inch fill depth produces 32 ft³ of net volume.
With 10% extra and 2 ft³ bags: ceil(32 × 1.10 ÷ 2) = 18 bags.
Assumptions and limits
- The inside is a rectangular prism.
- Existing fill has a reasonably uniform average depth.
- Bag volume is a filled-volume rating.
- Plant suitability, drainage, amendments, and recipe percentages are outside the quantity calculation.
Common measuring mistakes
- Using outside frame dimensions.
- Entering bag weight as bag volume.
- Letting soil-blend percentages add to more or less than 100%.
Sources
Product-specific values remain editable. These sources support the method and stated examples; they are not a universal substitute for your supplier’s current label.
- Formula basis: rectangular volume and package yield Geometry and unit conversions are documented in the GQ Calc methodology; package volume comes from the user’s label.
Questions people ask
Should I use inside or outside dimensions?
Use the interior space that soil actually occupies.
Can I subtract branches or filler?
Approximate their settled displacement as existing fill depth, or calculate their volume separately. The calculator does not judge whether a filler method is suitable.
How do I split a soil mix?
Apply your recipe percentages to the order volume and confirm that the shares total 100%.