Potting Soil Volume Calculator
Round Pot/Container
Calculate soil for round pots, buckets, and barrels
Rectangular Planter/Window Box
Calculate soil for rectangular planters and window boxes
By Common Pot Size
Quick lookup for standard pot sizes
Formula
Round Pot: Volume = π × r² × height | Rectangular: Volume = L × W × H | 1 cu ft ≈ 25.7 quarts ≈ 6.4 gallons
Frequently Asked Questions
How many quarts of soil for a 12-inch pot?
A standard 12-inch diameter pot needs about 8 quarts (2 gallons) of potting soil. This is based on an average pot depth of 10 inches, filled to 85% capacity to allow room for watering.
Can I reuse potting soil?
Yes, potting soil can be reused for 2-3 seasons. Refresh by mixing in 25% new compost, adding perlite for drainage, and optionally adding slow-release fertilizer. Remove old roots and check for pests. Do not reuse soil from diseased plants.
What is the difference between potting soil and garden soil?
Potting soil (potting mix) is lightweight, well-draining, and designed for containers. It typically contains peat moss, perlite, and compost. Garden soil is heavier, denser, and compacts in pots, leading to poor drainage and root rot. Never use garden soil in containers.
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