How this estimate works
A rectangular-container estimate multiplies inside length, width and fill depth. Real pots taper and need drainage space, so measure the inside and leave room below the rim. For a tapered pot, this result is an upper-bound estimate.
Worked example
A 12 × 12 × 10 inch rectangular planter is about 6.2 US gallons before leaving headroom.
Common mistakes
- Measuring the outside instead of the usable inside dimensions.
- Filling to the rim or forgetting the recommended spacing and drainage needs.
- Treating volume as an exact number of bags without checking package size.
Questions to check
What should I grow? Match the crop to your sunlight, climate and container depth. When should I plant? Check your local cooperative extension or USDA zone guidance; frost dates vary within regions.
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