Potting Soil Calculator
Calculate exactly how much potting soil you need for rectangular or round planters. Enter dimensions, number of planters, and bag size to get precise soil volume in cubic feet, liters, and bags needed with cost breakdown.
About This Calculator
Whether you are filling a single flower pot on your balcony or preparing dozens of planters for a community garden, knowing exactly how much potting soil to buy saves money, reduces waste, and ensures your plants have the right growing environment. The Potting Soil Calculator helps gardeners, landscapers, and plant enthusiasts determine the precise volume of soil needed for rectangular and round planters.
To calculate the soil volume, the calculator uses the geometric formula for your planter shape. For rectangular planters, volume = length × width × depth (in cubic inches). For round planters, volume = π × radius² × depth (in cubic inches). The total is then converted into multiple units — cubic feet, cubic yards, liters, quarts, and gallons — so you can match any bag size available at your local garden center. The calculator also estimates the number of bags required based on your selected bag size and the total cost when you provide a price per bag.
Regional Notes
India: Potting soil is commonly sold in 1 kg, 5 kg, and 10 kg bags or by cubic foot from nurseries. Convert weight-based bags using an approximate density of 0.5 kg per liter. Planter dimensions are typically measured in centimeters or inches; 1 cm³ = 0.061 cubic inches.
US: Bag sizes are typically 8 qt (0.27 cu ft), 16 qt (0.54 cu ft), 1 cu ft, 1.5 cu ft, and 2 cu ft. Prices range from $5–$15 per bag depending on brand and quality. Dimensions are measured in inches.
UK: Potting compost is sold in liter bags — common sizes include 10 L, 20 L, 25 L, 40 L, and 50 L. Use the calculator's liter output for easy matching. Planter dimensions are typically in centimeters; convert to inches by dividing by 2.54.
Frequently Asked Questions
How does the Potting Soil Calculator work?
The calculator determines the volume of potting soil needed based on your planter shape and dimensions. For rectangular planters it multiplies length × width × depth, and for round planters it uses π × radius² × depth. The total cubic inches are then converted to cubic feet, liters, quarts, and gallons, and divided by your chosen bag size to calculate how many bags to buy.
How much potting soil do I need for a standard 12-inch pot?
A standard 12-inch diameter round pot that is 10 inches deep requires approximately 0.65 cubic feet of potting soil, which is about 18.5 liters or 5 gallons. This typically fills one 0.75 cu ft bag or two 8-quart bags.
Should I use potting soil or garden soil for containers?
Always use potting soil (also called potting mix) for containers and planters. Garden soil is too dense and heavy for pots — it compacts in containers, reduces drainage, and can introduce pests and diseases. Potting soil is formulated with perlite, vermiculite, or peat moss for proper aeration and drainage.
Is this calculator free to use?
Yes, it is completely free to use with no registration or sign-up required. You can also share your calculation results via the URL.
How many liters are in a standard bag of potting soil?
In the US, common bag sizes include 8 quarts (7.6 L), 16 quarts (15.1 L), and 1 cubic foot (28.3 L). In the UK and Europe, potting soil is more commonly sold in liter sizes such as 10 L, 20 L, 25 L, 40 L, and 50 L bags. In India, potting mix is often sold in 1 kg, 5 kg, or 10 kg bags or loose by the cubic foot.
How much potting soil do I need for a raised bed?
For raised beds, use this calculator with rectangular shape. A typical 4 ft × 8 ft raised bed with 12-inch depth needs about 32 cubic feet of soil (approximately 16 bags of 2 cu ft potting mix or 1.2 cubic yards). For large raised beds, buying soil in bulk cubic yards is usually more cost-effective than individual bags.