Tank Capacity Calculator
Tank Capacity Calculator
Select your tank shape and enter its dimensions to find the volume in cubic feet, US gallons, and liters — useful for water tanks, septic tanks, and storage containers.
Cylindrical tank volume follows the standard circle-area formula (π times the radius squared) multiplied by height, which is why diameter — not radius — is the dimension usually printed on a tank's spec sheet, and it's easy to accidentally halve or double a result by mixing the two up. A 4 ft diameter tank standing 5 ft tall works out to roughly 62.83 cubic feet, or about 470 US gallons — this conversion between raw volume and gallons or liters is exactly what's needed when sizing a water storage tank against a household's known daily usage, or checking a septic tank's capacity against local code requirements.
- Imperial cylindrical: Volume = π × (Diameter ÷ 2)² × Height, in feet, converted to US gallons. Example: 4 ft diameter × 5 ft = 62.83 cu ft ≈ 470.1 gallons.
- Metric cylindrical: Volume = π × (Diameter ÷ 2)² × Height, in meters, converted to liters. Example: 1.2 m diameter × 1.5 m = 1.70 m³ ≈ 1696.5 liters.
- Rectangular: Volume = Length × Width × Height, in either unit system.
Does this account for wall thickness?
No — this calculates the interior volume based on the dimensions you enter; measure interior dimensions for the most accurate result.
Can I use this for a septic or water storage tank?
Yes — enter the tank's interior shape and dimensions to estimate its holding capacity.
Tank Capacity Calculator
Select your tank shape and enter its dimensions to find the volume in cubic feet, US gallons, and liters — useful for water tanks, septic tanks, and storage containers.
Cylindrical tank volume follows the standard circle-area formula (π times the radius squared) multiplied by height, which is why diameter — not radius — is the dimension usually printed on a tank's spec sheet, and it's easy to accidentally halve or double a result by mixing the two up. A 4 ft diameter tank standing 5 ft tall works out to roughly 62.83 cubic feet, or about 470 US gallons — this conversion between raw volume and gallons or liters is exactly what's needed when sizing a water storage tank against a household's known daily usage, or checking a septic tank's capacity against local code requirements.
- Imperial cylindrical: Volume = π × (Diameter ÷ 2)² × Height, in feet, converted to US gallons. Example: 4 ft diameter × 5 ft = 62.83 cu ft ≈ 470.1 gallons.
- Metric cylindrical: Volume = π × (Diameter ÷ 2)² × Height, in meters, converted to liters. Example: 1.2 m diameter × 1.5 m = 1.70 m³ ≈ 1696.5 liters.
- Rectangular: Volume = Length × Width × Height, in either unit system.
Does this account for wall thickness?
No — this calculates the interior volume based on the dimensions you enter; measure interior dimensions for the most accurate result.
Can I use this for a septic or water storage tank?
Yes — enter the tank's interior shape and dimensions to estimate its holding capacity.