Pots and potting mix
Potting Soil Bag Calculator and Pot Size Chart
Enter the bag size you have to compare potting mix per reference pot, full pots per package, and the number of bags needed for your selected pot count.
Calculator and chart
See how many pots one package can fill
Enter the package volume, then choose a reference nursery pot and quantity. The purchase estimate and full chart update instantly.
Quick reference
Potting mix needed by reference pot size
Based on 1 cu ft per package
| Reference pot | Planned per pot | Full pots per package |
|---|---|---|
| 3 in nursery pot (reference) | 0.26 US qt | 116 pots |
| 4 in nursery pot (reference) | 0.58 US qt | 51 pots |
| 5 in nursery pot (reference) | 1.42 US qt | 21 pots |
| 7 in nursery pot (6.7 in reference) | 3.15 US qt | 9 pots |
Planned per pot includes the selected fill level and allowance. It does not subtract an existing root ball.
Before you calculate
What this estimate can tell you
Potting mix packages are sold by volume, while nursery pots are usually described by top diameter. This calculator converts one reference nursery-pot line into estimated mix per pot, then compares it with a package in cubic feet, US quarts, US gallons, or liters. Select one pot size and quantity for a purchase estimate, or scan the table to compare all available sizes.
How are pots per bag estimated?
The tapered-pot volume is estimated with the frustum formula, then multiplied by the fill percentage and optional allowance. Full pots per package = package volume ÷ planned mix per pot, rounded down. Packages to buy = total planned mix for the selected pot count ÷ package volume, rounded up.
Assumptions and limits
- The quick chart uses labeled dimensions from one nursery-pot product line. A nominal 4-inch or 5-inch pot is not a universal capacity across brands.
- The chart estimates filling empty pots and does not subtract an existing root ball. Use the repotting soil calculator when the old root ball moves into a larger pot.
- Compressed package contents, moisture, settling, raised pot bases, and how firmly the mix is packed can change the number of pots filled.
- Full pots per package is rounded down to whole pots; a remainder may still be useful for smaller containers.
Worked example
Example: a 1 cu ft bag and 4-inch nursery pots
Using the 4-inch reference dimensions, a 90% fill level, and a 10% allowance, each pot needs about 0.58 US qt. A 1 cu ft bag can fill about 51 whole pots; twelve pots require about 7.0 US qt, so one bag is enough.
FAQ
Common questions
How many 4-inch pots will 1 cubic foot of potting mix fill?
With this tool's 4-inch reference pot, a 90% fill level, and a 10% allowance, the estimate is about 51 whole pots. Other 4-inch pots can be taller, wider at the base, or shaped differently, so treat the number as a planning estimate.
Why can two pots with the same inch size need different amounts of soil?
The inch size usually describes the top opening, not the height, bottom diameter, taper, or raised base. Enter actual inside dimensions in the full potting soil calculator when you need a closer estimate.
Does the chart subtract the plant's existing root ball?
No. It estimates filling an empty pot. Use the repotting soil calculator when the old root ball will occupy part of the new container.
Why does the table say less than one full pot?
The package volume you entered is smaller than the planned amount for that pot. The selected-pot result still shows how many complete packages are needed.
Should I enter potting soil in quarts or cubic feet?
Use the unit printed on the package. The calculator converts cubic feet, US quarts, US gallons, and liters to the same internal liter value before comparing them with the pot estimates.
Calculation references
- Botanically Unique: Clear Nursery Pot DimensionsUsed for the 3-, 4-, 5-, and 7-inch reference dimensions; nominal pot sizes are not universal capacities.
- NIST: SI Units — VolumeUsed to verify the relationship among cubic centimeters, liters, and package-volume conversions.