Fuel tank size calculator
Gallons in a diesel, gasoline or heating-oil storage tank — horizontal or vertical, round, rectangular or oval — from its dimensions, at any fuel level, with the weight of the fuel. Then print a tank chart for it.
Exact segment geometry — see methodology. Dished-head propane math is documented there too.
What to measure
Which shape is my tank?
- Round tank on a stand or skid — horizontal cylinder. Farm diesel and gasoline tanks, most aboveground bulk tanks and buried tanks.
- Upright round tank — vertical cylinder.
- Box or truck-bed transfer tank — rectangular; split an L-shaped tank into two boxes.
- Flat-sided oval basement tank — the 275 / 330 gallon oil tank shape, upright or on its side; see also the heating oil tank calculator.
- Round tank with rounded ends — capsule; for dished ends use the dished head tank calculator.
Weight of fuel
| Fuel | lb/gal | 100 gal | 275 gal | 500 gal | 1,000 gal |
|---|---|---|---|---|---|
| Diesel | 7.05 | 705 | 1,939 | 3,525 | 7,050 |
| Gasoline | 6.30 | 630 | 1,732 | 3,150 | 6,300 |
| Heating oil #2 | 7.20 | 720 | 1,980 | 3,600 | 7,200 |
| Kerosene | 6.82 | 682 | 1,876 | 3,410 | 6,820 |
Tank charts for fuel tanks
A tank chart turns a stick reading into gallons. Printed charts for common fuel tanks — 275 and 330 gallon oil tanks and 500 to 2,000 gallon underground tanks — are in tank charts; for any other size, the dip chart generator prints one from your dimensions. Where the manufacturer publishes its own chart, it is in the manufacturer tank registry.
Underground tanks at a business: the UST inventory worksheet does the monthly reconciliation. Tank on a slope? Use the tilt correction.
FAQ
How do I calculate the size of a fuel tank?
Measure the inside length, width and height of a rectangular tank, or the inside diameter and length of a round one, in inches. Rectangular: L × W × H ÷ 231 = US gallons. Round: π × radius² × length ÷ 231. For a round tank lying on its side, the gallons at a given depth need the circular-segment formula — enter it above and set the fill depth.
How do I work out an L-shaped truck transfer tank?
Split it into two boxes — the tall part and the low step — work out each one as a rectangular tank and add them. Measure the inside, or subtract the wall thickness from each outside measurement.
How much does a full fuel tank weigh?
Diesel weighs about 7.05 lb per gallon and gasoline about 6.30 lb, so a 100 gallon diesel tank holds about 705 lb of fuel. The table above covers common sizes; add the empty tank.
How full can I fill a fuel tank?
Leave room for the fuel to expand as it warms. How much depends on the temperature swing and the tank; the thermal expansion calculator works it out. Follow the tank maker's label and your fire code.
Can I make a tank chart for my fuel tank?
Yes — enter its dimensions in the dip chart generator for a printable inches-to-gallons chart, or print a 1:1 dipstick marked in gallons.
Sources and standards
- Methodology — partial-fill formulas and liquid densities used on this sitetankvolumecalc.comhttps://tankvolumecalc.com/methodology/
- Handbook 44, Appendix C — General Tables of Units of MeasurementNational Institute of Standards and Technology, U.S. Department of Commercehttps://www.nist.gov/document/2026-nist-handbook-44-appendix-cUS gallon = 231 in³ exactly.
Every linked source above was retrieved and checked on 2026-11-01.