Flower Pot Sizes: Diameter, Depth and Soil Volume

Flower pot size chart

The size on a pot is the diameter across the top, measured inside the rim in the US. Depth and base width are not standardized, but most round pots follow the same taper. The volumes below are calculated for a standard pot that narrows to about three-quarters of its top width at the base.

Volume rises with the cube of the size: doubling the diameter from 6 to 12 in multiplies the soil by about seven and a half. Real pots vary; a straight-sided cylinder of the same top size and height holds about 30% more, and a squat bowl much less. Soil is filled to about 1 in below the rim, so plan on roughly 10% less than the figures above.

12 in pot 12 × 10.5 in10 in pot 10 × 9 in8 in pot 8 × 7 in6 in pot 6 × 5.5 in

Pot depth: standard, azalea and bulb pan

Pots with the same top size come in three depths. The name tells you the height as a share of the diameter.

A shallow pot dries out faster at the top and holds less water in reserve, but it drains well and is harder to overwater, which suits succulents and cacti. Deep-rooted plants and anything you water infrequently do better in a standard or tall pot.

Nursery "gallon" pot sizes

Garden centers sell shrubs and perennials in black plastic containers labeled #1, #2, #3, #5 and so on, usually called 1-gallon, 2-gallon and so on. These are trade classes defined by volume ranges in ANSI Z60.1, the American Standard for Nursery Stock, and they hold less than the liquid gallon the name suggests.

Dimensions vary by manufacturer; check the label or the grower's catalog if the exact volume matters. When a recipe or plant tag asks for a "5 gallon container", a 12 to 14 in standard pot or a #5 nursery can matches it.

Metric pot sizes (cm and liters)

In Europe, the UK and Australia, pots are sold by diameter in centimeters, and nursery pots by liters. Pot diameters are often measured across the outside of the rim, so a 12 cm pot can be slightly smaller inside than a US 5 in pot.

Choosing the right pot size

1. Measure the current pot across the top, inside the rim.
2. Go up one step, not three. For pots up to 10 in, move up 1 to 2 in (2.5 to 5 cm) in diameter. For larger pots, 2 to 4 in. A pot far bigger than the root ball holds wet soil the roots cannot reach, which invites root rot.
3. Match depth to the roots. Use a standard pot for most plants, an azalea pot for shallow roots, and a bulb pan for succulents and bulbs.
4. Check the drainage. Every pot needs at least one hole. A decorative pot without holes should be used as a cachepot, with a plastic grower pot standing inside it, so the outer pot must be 1 to 2 in wider than the grower pot.
5. Add a saucer that fits the base. Measure the bottom of the pot and choose a saucer at least 1 in (2.5 cm) wider than that. For a standard 10 in pot with a 7.5 in base, an 8 to 10 in saucer works.

Hanging basket sizes

Hanging baskets are sold by top diameter, and most are roughly half-spheres. Wire baskets lined with coir hold about the volume below; plastic baskets with built-in reservoirs hold a little less.

Watered, a 14 in basket can weigh 20 to 30 lb (9 to 14 kg); use a bracket and hook rated for at least that. Square, rectangular and large patio containers, window boxes and raised beds are covered in the planter size guide.

To water pots without flooding them, a hose with a shut-off nozzle helps; see garden hose sizes. For arranging pots on a patio or deck around furniture, the patio furniture dimensions, outdoor furniture sizes and deck size guides give the footprints. Cooking pots are a different sizing system entirely, covered in pots and pans sizes.

Frequently asked questions