Oil and propane tank calculator
Pick your tank and enter the dip reading to see the gallons left. For propane, switch to the Propane tab and enter the gauge percent. Dated readings further down estimate when the tank runs low.
How the numbers are worked out
- The volume at each depth comes from the shape of the tank's cross-section. An oval-ended tank is a rectangle with a half circle at each end, and the oil at a given depth fills part of that shape. Round tanks lying down use the same circle math. Upright round tanks and boxes fill evenly, so each inch holds the same amount.
- The chart runs to the very top of the tank. Tanks are not filled that far: InspectAPedia notes a 275 gallon tank may be marked "Maximum Fill 247 gallons", leaving about 6 in of air at the top. PickHVAC puts the usual maximum fill for a 275 at 220 to 248 gal.
- A 27 × 44 × 60 in tank works out to 267.9 gal by its shape, a little under the 275 on the label. My guess is that the outside size includes the steel and the rounded seams, and the label is a round number.
- A tank that leans toward one end reads differently at each end. Dip at the middle of the tank if you can.
- US gallons are 231 cubic inches. Liters are 1,000 cubic centimeters.
Where the preset sizes come from
- 275 and 330 gal oval-ended tanks: InspectAPedia's oil tank size table (44 × 60 × 27 in and 44 × 72 × 27 in).
- Round tanks lying down: the Modern Welding UL-142 brochure (48 × 72 in, about 560 gal; 64 × 72 in, 1,000 gal).
- Roth DWT 275: a retailer listing (28 × 43 × 65 in). The oil sits in a blow-molded inner tank, so the box shape is an approximation.
- Titan EcoSafe tanks: the Kingspan product selector (03/2026) for outside sizes and capacities.
Guides
- 275 gallon oil tank chart: standing and lying down, every inch, and how to dip.
- How long will heating oil last: the run-out math with a worked example.
- 1200 litre oil tank chart: bunded plastic tanks in the UK and Ireland, by depth in cm.
- 500 gallon propane tank chart: gauge percent to gallons, and how long a tank lasts.
- 1000 gallon propane tank chart: gallons by gauge percent, days to 20% for a whole house and fills per year.
- 120 gallon propane tank chart: gallons by gauge percent, and how long 96 gal lasts with a water heater, range or fireplace.
- Propane tank percentage chart: gauge percent to gallons for 120 to 1,000 gal tanks, side by side.
- How much propane does a furnace use per day: gallons per hour and per day from your furnace's rating and the weather.
- Heating fuel cost comparison: oil, propane, gas, electric, heat pump, pellets and wood per million Btu, at your prices.
- Heat pump vs oil heating cost: the electricity price where a heat pump matches oil, by COP and oil price.