Tank Volume Calculator
Pick a shape and enter its dimensions to get total tank capacity in gallons and liters.
How it works
Rectangular tank volume is length × width × height. Vertical cylinder volume is π × radius² × height. In Imperial units, cubic inches convert to US gallons by dividing by 231 (1 US gallon = 231 in³). In Metric units, cubic centimeters convert to liters by dividing by 1,000 (1,000 cm³ = 1 L).
Worked example
Imperial: A rectangular tank 48 in × 24 in × 24 in holds 27,648 in³, which equals 119.7 gallons (16.0 cu ft).
Metric equivalent: 121.9 cm × 61.0 cm × 61.0 cm holds 453,592 cm³, which equals 453.6 liters (0.45 m³).
Assumptions
- Tank walls are thin enough that inside dimensions ≈ outside dimensions; use inside dimensions for best accuracy.
- Volume is total/nominal capacity — real-world usable volume is often slightly less due to fittings or an outlet above the floor.
Reference
Standard volume formulas for rectangular prisms and cylinders: Wikipedia — Volume.
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Frequently asked questions
How many gallons are in a cylindrical tank?
Multiply the cross-sectional area (π × radius²) by the height, then divide by 231 for US gallons.
How do I calculate the volume of a rectangular tank?
Multiply length × width × height for cubic inches, then divide by 231 for US gallons.
What if my tank is a horizontal cylinder?
Use the fuel tank capacity calculator, which supports horizontal cylinders, or the fill-level calculator for partial-fill volume.