Enter your values
The starting values are editable examples. Results update when you change your inputs.
Your result
Updates as you change your values.
How it is calculated
Rectangle: V = length × width × depth. Cylinder: V = πr²h. Frustum: V = πh(R² + Rr + r²) / 3. Divide cm³ by 1,000 for litres, deduct reserved volume and round bags up.
Worked example
A 100 × 30 cm rectangular planter filled to 20 cm holds 60 litres. Reserving 10% leaves 54 litres of substrate, requiring three 20 L bags.
Before you calculate
Measure inside the planter and use the depth you actually want to fill. Select the shape before entering its dimensions. For a tapered planter, top and bottom diameters describe the filled portion. Reserve volume for features that displace substrate, rather than adding it again to the depth.
Interpreting the result
The geometric result does not predict compaction, settling or root-ball volume unless you account for them. Bag quantities are rounded up from the labelled loose volume. Check drainage and the suitability of the growing medium separately.
Use the units shown beside each field. Monetary fields labelled EUR stay in euros; changing language does not exchange currencies. Results are estimates under the stated assumptions.