Free local container planner
Measure the pot.
Buy the mix.
Use the inside dimensions and fill depth you actually plan to use. Get the total potting-soil volume and a whole-bag starting point before you shop.
1 · Measure inside the container
Volume, not growing advice
Leave the rim space you want.
For round containers, this calculator uses the cylinder formula: π × radius² × fill depth. For rectangular planters, it uses length × width × fill depth. It converts cubic inches to dry quarts and US gallons, then rounds bags up only at the end.
Measure inside the container at the soil line. Set fill depth below the rim if you want headspace, and use the dry-quart amount printed on the bag you are considering. Container shape, tapered walls, drainage layers, settling, moisture, and the actual product can all change what fits.
This tool does not choose a potting mix, assess plant suitability, calculate fertilizer, predict drainage or water needs, verify a bag's contents, or guarantee plant health. See Oregon State Extension's container-gardening basics ↗