Potting mix for a 20-inch pot at each fill depth
These figures are for a pot with straight sides, measured across the inside of the rim. Potting mix is sold by the dry quart or the cubic foot; bag counts are rounded up.
| Fill depth | Cubic feet | Liters | Dry quarts | Bags of 8 qt | Bags of 16 qt | Bags of 1 ft³ | Bags of 2 ft³ |
|---|---|---|---|---|---|---|---|
| 6 in | 1.091 | 30.9 | 28 | 4 | 2 | 2 | 1 |
| 9 in | 1.636 | 46.3 | 42.1 | 6 | 3 | 2 | 1 |
| 12 in | 2.182 | 61.8 | 56.1 | 8 | 4 | 3 | 2 |
| 15 in | 2.727 | 77.2 | 70.1 | 9 | 5 | 3 | 2 |
| 18 in | 3.272 | 92.7 | 84.1 | 11 | 6 | 4 | 2 |
| 20 in | 3.636 | 103 | 93.5 | 12 | 6 | 4 | 2 |
If the pot narrows toward the base
A tapered pot holds less than a straight-sided one of the same rim size. Measure the inside diameter at the top and at the bottom, then use the tapered-pot option in the soil calculator, which works out the volume of the cone-shaped section you will fill. Leave the space you want free at the top out of your fill depth.
Work out your own bed
Open these measurements in the soil calculator to change the depth, add more beds or split the fill into a mix. For a group of pots, add each one to the calculator as its own container.