Potting Soil Calculator

About this calculator

Filling containers with potting soil comes down to a volume calculation: for a cylindrical pot, volume equals π × radius² × height, and gardeners with several pots of different sizes need the sum of each container’s volume before they know how much soil to buy. Because potting mix is sold by bag in fixed volumes — commonly 1 cubic foot, 8 quart, 20 quart, or 50 liter bags depending on the brand and region — the last step is converting the total cubic volume needed into a whole number of bags, rounding up since partial bags aren’t sold.

This calculator takes container dimensions and count, computes the combined volume, and converts it into the number of bags required for a given bag size, saving a trip back to the garden center for one more bag or an unopened bag left over. It’s the kind of quick estimate home gardeners, container growers, and landscapers reach for before a potting or repotting session, since soil volume needs scale directly with pot diameter squared — a modest increase in pot size uses noticeably more mix than it looks like it would.