How to use the Garden / Raised Bed Cubic Feet Calculator
- Use the inside length and width, then the depth of soil being added. Existing soil reduces the new fill depth.
- Choose length and width or a known coverage area. Enter depth, allowance and actual package yield; add supplier density or price only when needed.
- Select Calculate. Review the result and its working; if you change an input, calculate again before copying or sharing.
Garden / Raised Bed formula
First calculate the geometric fill volume. Apply the entered percentage allowance to that volume, then divide by product yield and round up to whole bags.
Base volume = area × depth; order volume = base × (1 + allowance ÷ 100); bags = ceil(order volume ÷ bag yield)
What the terms mean
- Length
- A measured length in the selected unit; it is converted to feet before volume is calculated.
- Width
- A measured length in the selected unit; it is converted to feet before volume is calculated.
- Coverage area
- The measured area to cover, expressed in the selected square unit.
- Fill depth
- A measured length in the selected unit; it is converted to feet before volume is calculated.
- Extra volume allowance
- A percentage added to the geometric volume for the planning assumption you choose.
- Volume per bag
- Use the actual bag label; the starting value is an example.
- Bulk density (optional)
- Entered in lb/ft³.
- Price (optional)
- Price per selected bag, volume unit or US short ton; use one currency consistently.
Garden / Raised Bed worked examples
Estimate a shallow soil top-up
A 10 ft × 6 ft bed needs a 3 in soil top-up. Add 5% extra volume and use 1.5 ft³ bags.
- Area 60 ft² × depth 0.25 ft = 15 ft³
- Order volume = 15 × (1 + 5 ÷ 100)
- Bags = round up (15.75 ÷ 1.5)
Answer: 15.75 ft³. Base volume: 15 ft³; Cubic yards: 0.583333 yd³; Litres: 445.990334 L; Whole bags: 11 bags.
Fill an eight-by-four raised bed
An 8 ft × 4 ft bed needs 12 in of soil. Use 2 ft³ bags and no extra allowance.
- Area 32 ft² × depth 1 ft = 32 ft³
- Order volume = 32 × (1 + 0 ÷ 100)
- Bags = round up (32 ÷ 2)
Answer: 32 ft³. Base volume: 32 ft³; Cubic yards: 1.185185 yd³; Litres: 906.139091 L; Whole bags: 16 bags.
Garden / Raised Bed Cubic Feet Calculator FAQs
Can I subtract an existing soil layer?
Enter only the remaining depth to be filled. For different depths, measure separate areas.
Do I need to allow for settling?
Enter a percentage based on your mix and supplier guidance. The default is an editable example.
Measurement guide for Garden / Raised Bed
Measure the inside of the bed and the depth of soil to add, rather than the full wall height. Exclude existing soil and unfilled space above the surface.
Assumptions and limits
Beds can taper or contain drainage layers. Use the soil footprint and depth rather than automatically using the full external bed dimensions.
Bag yield and bulk density depend on the actual product. Allowance is applied to volume; bags are rounded up.
Check your result
Compare the base volume with area multiplied by depth in feet. The order volume includes your allowance; a bag count is rounded up using the entered product yield.