Bagged potting mix is sold in US dry quarts and bulk soil is sold in cubic feet, so converting between them is the first sum most people hit. One cubic foot is 25.71 US dry quarts. A 25 quart bag is therefore 0.97 cubic feet, or 27.5 liters — just under a cubic foot, not the one-for-one swap it looks like.
The converter above goes both ways between dry quarts, liquid quarts, US gallons, cubic feet, cubic yards and liters.
How to use it
Enter a number, pick the unit it is measured in, and read off every other unit.
Most people come here holding a bag and wanting cubic feet, so entering dry quarts gives cubic feet as the headline. Enter cubic feet or cubic yards and it flips: the headline becomes dry quarts, because at that point you are working out how many bags to buy.
The metric toggle changes which units lead, not the arithmetic. The full table underneath always shows all six.
How it is calculated
Everything routes through cubic feet, using exact definitions rather than rounded conversion factors.
- US dry quart = 67.200625 cubic inches exactly, so 1 cu ft = 1728 / 67.200625 = 25.714 dry quarts
- US liquid quart = 57.75 cubic inches exactly, so 1 cu ft = 29.922 liquid quarts
- US gallon = 231 cubic inches, so 1 cu ft = 7.481 gallons
- Cubic yard = 27 cubic feet
- Liter = 1 cu ft x 0.3048³ x 1000 = 28.317 liters
The dry-versus-liquid distinction is the one that costs money. They are genuinely different units that share a name: the dry quart is about 16% larger. A great many calculator pages quote 29.92 quarts per cubic foot for potting soil, which is the liquid figure, and anyone following it buys 16% too few bags.
A worked example
A raised bed needs 12 cubic feet of mix, and the shop sells 32 quart bags.
- 32 dry quarts = 32 / 25.714 = 1.24 cubic feet per bag
- 12 / 1.24 = 9.6 bags, so ten
- Using liquid quarts instead: 32 / 29.922 = 1.07 cu ft, giving 11.2 bags — twelve
The liquid figure has you buying two extra bags here. In the other direction — working out what a bag will fill — the same error leaves you short.
Bag sizes in cubic feet and liters
| Bag size | Cubic feet | Liters | Rough weight |
|---|---|---|---|
| 4 dry qt | 0.156 | 4.4 | 2–6 lb |
| 8 dry qt | 0.311 | 8.81 | 4–12 lb |
| 16 dry qt | 0.622 | 17.6 | 7–25 lb |
| 25 dry qt | 0.972 | 27.5 | 12–39 lb |
| 32 dry qt | 1.24 | 35.2 | 15–50 lb |
| 50 dry qt | 1.94 | 55.1 | 23–78 lb |
| 64 dry qt | 2.49 | 70.5 | 30–100 lb |
Weights use 12 to 40 lb per cubic footEstimate: no extension source was found for the bulk density of bagged growing medium, so it is a typical published value rather than a checked one., which is a typical published spread rather than a checked figure.
What soil weighs, and why this is a range
People search for the weight of a quantity of soil, usually to work out whether they can carry it or what a car will take. The honest answer is a range.
Bulk density of a growing medium depends on what is in it and how wet it is. A dry peat-and-bark potting mix is light; the same bag after a week in the rain can weigh more than twice as much, because the water is heavier than the medium holding it. Mixes cut with compost, sand or loam are heavier again from the start.
So the figures above use 12 to 40 pounds per cubic foot, and that spread is the answer rather than an apology for one. A single number would be wrong for almost everyone using it, and wrong by enough to matter if you are deciding what a car boot will hold.
Bagged topsoil and garden soil are a different material and much heavier — roughly 75 to 100 pounds per cubic foot. A cubic foot of topsoil is a two-hand lift; a cubic foot of dry potting mix is not. The range on this page is for potting and container mixes, and applying it to topsoil would understate the weight by a factor of three.
Neither range is verified against an extension source. The data verification this site ran in September 2026 covered crop spacing, compost feedstocks, lime and grass seed; nothing in its appendix gives a bulk density for bagged potting mix. Both figures are therefore carried as estimates and marked as such wherever they appear, rather than being presented as checked.
Tips and common mistakes
Check whether a bag is labelled in quarts or cubic feet before comparing prices. A 2 cubic foot bag holds 51.4 dry quarts, so it is more than twice a 25 quart bag despite looking like a similar object on the shelf.
Do not assume a "quart" on a foreign label is a US quart. An imperial quart, still seen on some Canadian and UK packaging, is 69.36 cubic inches — close to the US dry quart and nothing like the US liquid one.
Bags settle. A bag is filled by volume at the plant and compresses in transit, so what comes out is usually a little less than the label after it has been broken up. Ordering to the exact figure leaves no margin.
Around 25 to 30 bags, get a bulk delivery. A cubic yard is about 28 of the 25 quart bags, and bulk is almost always cheaper per unit at that point — as well as one delivery instead of a car full of plastic.
Working the other way round, from a container or a bed to the volume you need, is what the container potting soil calculator and the raised bed soil calculator are for. This page is for when you already have the number and need it in a different unit.