A worked example
A 30 / 20 cm planter filled to 25 cm holds about 12.435 L. Four pots plus 5% need 52.229 L, or 3 bags of 20 L.
Planter soil
Estimate soil for a round, tapered planter using the diameters at the fill line and base.
YOUR LITTLE WORKBENCH
Planter soil
Start with the example, then make it your own. Results update as you type.
How this is calculated
V = πh(D² + Dd + d²) ÷ 12. Diameters D and d are measured inside the planter.
YOUR PLAN / LIVE RESULT
Planned buying volume
52.229 L- Geometric volume
- 49.7419 L
- Whole bags to buy
- 3
- Volume in whole bags
- 60 L
- Buying volume
- 1.8444 ft³
- Buying volume
- 0.0683 yd³
- Soil per pot
- 12.4355 L
This model assumes a straight-sided circular frustum. Measure the diameter at the intended soil line. Root balls, drainage material and irregular curves are not subtracted automatically.
THE METHOD / 01
Know what goesinto your result.
V = πh(D² + Dd + d²) ÷ 12. Diameters D and d are measured inside the planter.
Keep the assumptions clear
This model assumes a straight-sided circular frustum. Measure the diameter at the intended soil line. Root balls, drainage material and irregular curves are not subtracted automatically.
A FEW USEFUL ANSWERS
Good to know.
Are my inputs uploaded?
No. Calculations run locally in your browser. The host still receives normal requests for website pages and assets.
Can I keep my result?
Export a CSV, or use Print / PDF and choose Save as PDF in your browser. Inputs are not saved between visits.
Do I need an account?
No sign-up, paid API or subscription is required. Both language versions use the same calculation logic.
GROWKIND / TOOLKIT
A little help for every step.
01
Raised bed soil
Calculate the soil volume and whole bags for rectangular raised beds, with your own extra allowance.
Open tool03
Plant spacing
Lay out an aligned planting grid with equal border clearances. See how many rows and plants fit.
Open tool04
Mulch coverage
Turn a rectangular area and layer depth into litres, cubic yards and whole bags of mulch.
Open tool