Tank Volume Calculator
Type a horizontal tank's radius or diameter, its length and the liquid's depth, and read how much it holds in litres and gallons, plus its full capacity. The partial fill is the exact circular-segment result, not a guess from the fraction of the height, and the formula is shown with the working under it.
Tank · L × segment(r, f)50% of 3.14159 m³ when full · 1,570.8 L · 414.96 US gal · 345.527 UK gal
A cylinder lying on its side: an oil tank, a water tank, a tanker. The fill depth is measured up from the bottom; 0 is empty and the diameter is full.
The formula is on the stage, and the working is the first row. Every answer here is one textbook formula with your numbers put in, printed so you can check it: a cylinder is π r² h, a sphere is (4/3) π r³, a pool is length times width times the average of its two depths. The horizontal tank uses the exact circular-segment formula for a partial fill, so half way up is exactly half and a quarter of the way up is less than a quarter, because the bottom of a circle is narrow. Conversions use exact definitions: a litre is 1,000 cm³, a US gallon is 231 cubic inches and a UK gallon is 4.54609 litres.
Common questions
- How does the fill depth work?
- The tank is a cylinder on its side, and the fill depth is how high the liquid stands, measured up from the bottom of the tank. 0 is empty, and the full diameter is a full tank; a depth greater than the diameter is refused with a message saying what the tank's depth is. The tool works out the area of the circular segment the liquid covers, r² acos((r − f)/r) − (r − f) √(2rf − f²), and multiplies it by the length.
- Why is a quarter of the depth not a quarter of the volume?
- Because a circle is narrow at the bottom and widest in the middle. A tank of radius 1 m and length 2 m holds 6.283 m³ full and exactly half that, 3.142 m³, at 1 m of depth; at 0.5 m, a quarter of the way up, it holds 1.228 m³, which is 19.6% of the tank, not 25%. The stage says what percentage of the full tank the fill depth holds, and the When full row gives the capacity.
- What about a vertical tank, standing on its end?
- Pick Cylinder instead. A vertical tank's liquid is a shorter cylinder, so type the tank's radius or diameter and the depth of the liquid as the height, and the answer is the liquid's volume. Type the tank's full height for its capacity.
- Should I measure the radius or the diameter?
- Whichever is easier. The diameter is the full width across the end, which is what a tape measure gives you; the switch beside the field takes either and halves a diameter before it goes into the formula, and the formula line says r = d/2 when it did. Use the inside measurement for the liquid, since the wall takes up space.
- How many litres or gallons is that?
- The rows under the answer give litres, US gallons and UK gallons every time, whichever unit you measured in, plus cubic units for the scale you used. A US gallon is 231 cubic inches, which is 3.785411784 litres, and a UK gallon is 4.54609 litres; a 1,000 litre tank is 264 US gallons or 220 UK gallons.
Volumes are computed from the formulas shown, exact for the dimensions you type; a horizontal tank's partial fill is the exact circular-segment result. A US gallon is 231 cubic inches and a UK gallon 4.54609 litres.