A LITTLE PLANNING. A GREENER CORNER.
Soil calculator.
Just enough bags.
Turn a collection of pots into one practical shopping list. Measure the inside, count what you have, and leave room to grow.
No signup · Saved in this browser · Free01 / YOUR PATCH
What are you filling?
Use internal measurements. A group contains identical containers.
Saved locally when browser storage is available.
Shared links include all your plan details.
THE MEASURING-TAPE PART
A little air.
A little allowance.
Measure the usable inside of each container, including its bottom diameter if it narrows. The gap below the rim stays empty.
The RHS container-planting guide explains why a gap helps keep compost from spilling during watering. Choose a suitable growing medium for your plants; this tool estimates volume, not a soil recipe.
A trough 60 × 20 × 20 cm with a 2 cm gap holds 21.6 L. Two need 43.2 L. If you already have 10 L, one 40 L bag covers the remaining 33.2 L, leaving about 6.8 L.
How is the volume calculated?
A box uses length × width × filled depth. A round straight pot uses π × radius² × filled depth. A tapered round pot uses a circular-frustum formula, including its narrower diameter at the soil line. Cubic centimetres are divided by 1,000 for litres; 1 cubic foot is 28.316846592 L.
Why might the real amount be different?
These are geometric estimates. Root balls, drainage inserts, irregular walls, settling and compaction change the amount of loose soil needed. They are not modeled. Enter your best internal measurements and use the optional extra only if it suits your project.
What does existing soil mean?
It is suitable loose soil you already own and intend to use, not the volume already occupied by roots inside a planted pot. We subtract it after adding your extra allowance, then round the remaining need up to whole bags.
Are the prices or products recommendations?
No. Prices and bag sizes are editable examples. The cost includes bags only, excluding tax, delivery, plants and other supplies. Currency changes only the label; it does not convert prices.
How do saves and links work?
Your latest valid plan is saved in this browser if storage is available. A shared link contains an editable copy; anyone with it can read the measurements and names. Invalid or unsupported saved plans are rejected. No account is needed.