Be precise with your garden planning. Use our custom calculator to determine the exact volume of soil, compost, or custom mixes required for your rectangular, circular, or corner raised beds.
Container, raised-bed and potting-mix planner
Measure the volume you need, divide it into recipe components and compare bagged and bulk purchases.
Formula and worked example
Box: V = length × width × fill depth. Cylinder: V = πr²h. Tapered pot: V = πh(R² + Rr + r²) ÷ 3. A right-triangle bed uses half the box volume.
Example: a 30 cm diameter cylindrical pot filled to 25 cm holds 17.67 liters before rootball displacement or settling allowance. Subtract displacement per container, multiply by the count, then multiply by (1 + allowance ÷ 100). Component volume = total × fraction ÷ 100; round each shopping quantity up separately.
Read Kathy’s soil and nutrients guide, olive tree potting guidance and pumice and lava rock guidance, or open the standalone substrate planner.
How to Measure Your Raised Beds Accurately
To get the most accurate results from the volume engine above, follow these quick field practices:
- Measure Internal Dimensions: Always measure the interior walls of your raised frames. Thick construction timber (such as 2x4s or 4×4 posts) can artificially inflate your external measurements, causing you to over-order material.
- Calculate for Settling: Brand new soil blends contain high percentages of organic matter that compress and settle after the first few deep watering. We recommend calculating your depth to sit roughly 1 to 2 inches below the top rim, but adding a 5% to 10% volume buffer to compensate for compression over the first season.
- Choose the Right Mix: Selecting the appropriate option in the calculator dynamically alters the component breakdown, giving you exact yardage or liter requirements for specific raw materials.
