How to use the Soil Cubic Feet Calculator
- Use interior planter dimensions and actual fill depth. Enter the volume printed on the soil bag.
- 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.
Soil 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.
- Actual yield per bag
- Illustrative starting value. Replace with the volume or yield printed on your product.
- Bulk density (optional)
- Enter the supplier’s density for weight. Zero hides the weight estimate.
- Price (optional)
- Price per selected bag, volume unit or US short ton; use one currency consistently.
Soil worked examples
Estimate soil for a shallow planting area
A 10 ft × 6 ft planting area needs a 3 in layer of soil. 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.
Estimate soil from measured coverage
A 100 ft² area needs a 2 in layer with no extra allowance. Use 1.5 ft³ bags and an illustrative bulk price of 10 currency units per yd³.
- Area 100 ft² × depth 0.166667 ft = 16.666667 ft³
- Order volume = 16.666667 × (1 + 0 ÷ 100)
- Bags = round up (16.666667 ÷ 1.5)
Answer: 16.666667 ft³. Base volume: 16.666667 ft³; Cubic yards: 0.617284 yd³; Litres: 471.947443 L; Whole bags: 12 bags; Estimated cost: 6.17284 currency units.
Soil Cubic Feet Calculator FAQs
Should I fill to the top of the bed?
Use your intended soil depth, allowing any freeboard or mulch layer separately.
Why are bag counts rounded up?
A partial bag cannot supply the full required volume. Bag counts use the order volume including your entered allowance.
Measurement guide for Soil
Measure the space that needs filling, excluding existing soil and large obstructions. Use the labelled volume of the purchased soil bags.
Assumptions and limits
Bagged mix can settle after watering. Density and settling depend on the mix; enter your own allowance rather than treating it as a universal value.
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.