Fill pots by geometry

Pot & container soil calculator

Estimate mix for round or rectangular containers, multiply a whole set, and convert to common bag sizes.

Live worksheet

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Each field explains what to measure, where to find it, and how to read the result. Change any value to update the plan instantly.

Inside diameterinMeasure straight across the pot opening through its center, from inner wall to inner wall.Example: A pot sold as 14 in may have a slightly smaller inside diameter.Usable fill depthinFrom the inside base to your intended soil line. Leave headspace below the rim for watering.Example: A 14 in-tall pot might use 12 in of mix.Matching containersHow many containers have these same inside dimensions. Calculate different sizes separately.Example: Enter 3 for three matching pots.Planning reserve%Extra mix for settling, spillage, and tapered-pot estimation.Example: 10% is a practical starting allowance.Bag sizecu ftThe volume printed on one bag, not its weight.Example: A US bag might read 1.5 cu ft.

Potting mix plan

3.5cubic feet

Liters100

US gallons26.4

Whole bags3

Straight-sided geometry is an estimate for tapered or sculpted pots. Use inside dimensions and leave watering headspace.

Sources & further reading

Types of containers for growing vegetablesUniversity of Maryland Extension
Growing media for containersUniversity of Maryland Extension

Tell us what you are working with

A ‘10-inch pot’ does not tell you its soil volume

Sources & further reading