Fuel Weight Calculator converts fuel volume to weight, or weight back to volume, using the density of the fuel you pick and correcting it for temperature, from avgas to bunker oil.
How the Fuel Weight Calculator Turns Gallons Into Pounds
The Fuel Weight Calculator converts a volume of fuel into its weight, or a weight back into volume. Truck owners use it to check payload, pilots use it for weight and balance, and fuel haulers use it to stay under axle limits.
Pick a fuel, enter the amount, and set the fuel temperature. Volume can be US gallons, liters or UK gallons. Weight can be pounds or kilograms, and density can be lb/gal or kg/L.
The Fuel Weight Calculator Formula
Weight is volume times density. That part is exact physics, not an estimate.
$$\text{Weight} = \text{Volume} \times \text{Density}$$
To go the other way, divide the weight by the density.
$$\text{Volume} = \frac{\text{Weight}}{\text{Density}}$$
Each fuel in the list carries a typical density at 15°C (59°F). The tool converts every entry to liters and kilograms before it multiplies. It uses exact unit definitions, with 1 US gallon at 3.785411784 liters and 1 pound at 0.45359237 kilograms.
With the defaults, 20 US gallons of diesel at 60°F weighs 140.14 lbs. That is about 7.01 lbs per gallon, or 0.840 kg per liter.
A common mistake is typing a lb/gal figure while the density menu is set to kg/L. Diesel at 7.01 kg/L would weigh seven times as much as water, so check that the density unit matches the number.
Why Cold Fuel Weighs More
Fuel shrinks as it cools. The same gallon holds more mass on a cold morning than on a hot afternoon.
The Fuel Weight Calculator adjusts density with a thermal expansion rate for each fuel. This is a linear approximation, not the full standard.
$$\rho_T = \frac{\rho_{15}}{1 + \alpha\,(T – 15)}$$
Here ρ15 is the density at 15°C, T is the fuel temperature in °C, and α is the expansion rate. For diesel the tool uses 0.00083 per °C.
Custody transfer, where fuel is bought and sold in bulk, uses the volume correction tables in ASTM D1250 (API MPMS Chapter 11.1). Those tables correct US volumes to 60°F, while the metric procedures use 15°C or 20°C. The small gap between 60°F and 15°C is why the tool’s standard reference sits at 60°F while its density field reads at 15°C.
The third result card shows how much the weight changes per 10 degrees. The same 20 gallons of diesel weighs 141.97 lbs at 32°F and 137.91 lbs at 95°F. That is a 4 lb swing with no change in volume.
Propane reacts far more strongly. Liquid propane expands about 1.5% per 10°F, so 100 gallons drops from about 420 lbs at 60°F to about 402 lbs at 90°F. ASTM D1250 excludes LPG entirely, which is why propane is measured with separate tables.
Pounds per Gallon by Fuel
The alert box under the results shows the density range the governing spec allows for the fuel you picked. Here are the main ones, converted to pounds per US gallon.
| Fuel | Spec | Density range | Lbs per US gallon |
|---|---|---|---|
| Gasoline | EN 228 | 720–775 kg/m³ at 15°C | 6.01–6.47 |
| Diesel | EN 590 | 820–845 kg/m³ at 15°C | 6.84–7.05 |
| Jet A / Jet A-1 | ASTM D1655 | 775–840 kg/m³ at 15°C | 6.47–7.01 |
| Renewable diesel (HVO) | EN 15940 | 765–800 kg/m³ at 15°C | 6.38–6.68 |
| DEF | ISO 22241 | 1,087–1,093 kg/m³ at 20°C | 9.07–9.12 |
Aviation uses fixed planning values instead of a range. The FAA Aircraft Weight and Balance Handbook uses 6 lbs per gallon for avgas and about 6.7 lbs per gallon for Jet A. The calculator lands on 6.00 and 6.71 at 15°C, in line with those figures.
The second result card of the Fuel Weight Calculator shows the density at your fuel temperature. It also gives the weight of one UK gallon and of a full 55-gallon drum, fuel only.
Diesel vs. Gasoline Weight
In the fourth card, the Fuel Weight Calculator fills the same volume with a second fuel so you can compare. At the defaults, 20 gallons of diesel weighs 15.87 lbs more than 20 gallons of gasoline, which comes to 124.27 lbs.
Diesel is heavier because it is made of longer, denser hydrocarbon chains. The same card also shows the weight of that volume of water, 166.74 lbs here. Every fuel except DEF weighs less than water, which is why spilled fuel floats.
The first card repeats your result in the other weight units. With the defaults, that is 63.57 kg, 0.070 US short tons and 0.064 metric tonnes.
Solving for Gallons From a Weight Limit
Switch Solve For to Volume from Weight when you know the weight you can carry. Enter the weight, and the Fuel Weight Calculator returns the volume that fits.
A pilot with 500 lbs of useful load left for fuel can carry about 74.5 gallons of Jet A at 59°F. In this mode the third card shows how much extra space the same weight takes when the fuel warms up.
The first card lists the same volume in UK gallons and cubic feet, which helps when sizing a tank. To see how many gallons a given distance burns in the first place, the fuel cost calculator works that out from your MPG.
Input Limits and Edge Cases
Amount and density must be greater than zero. Temperature can be negative, but the Fuel Weight Calculator rejects anything at or below absolute zero, where the math stops making sense.
The alert box turns to a warning if density falls below 0.4 kg/L or above 1.2 kg/L. That range covers every liquid fuel and DEF, so a value outside it usually means a typo or the wrong unit.
It also warns when fuel temperature is below −40°F or above 140°F. Those readings sit outside normal storage and use.
The results cover fuel only. Tank, drum and cylinder weights are not included.
Mistakes That Throw Off Fuel Weight
Mixing up US and UK gallons skews the result by about 20%. A UK gallon holds 4.54609 liters, so check which gallon your tank or gauge uses.
Typing your own density switches the Fuel Weight Calculator to Custom Density. The tool then uses a general expansion rate of 0.09% per °C, so enter a density measured at the actual fuel temperature for liquids with a very different rate.
Weighing a drum or tank on a scale and entering that number as fuel weight overstates the fuel. Subtract the empty container weight first, since a steel drum or propane cylinder adds real weight of its own.
Fuel Weight Questions People Ask
How much does a gallon of diesel weigh?
About 7 pounds per US gallon at 60°F. EN 590 allows 820 to 845 kg/m³ at 15°C, which works out to 6.84 to 7.05 lbs per gallon. Winter blends and fuels with a kerosene share sit toward the lighter end. Biodiesel is heavier, with B100 around 7.34 lbs per gallon at the tool’s default density.
Why does diesel weigh more than gasoline?
Diesel molecules are larger and pack more mass into each gallon. Gasoline sits near 6.2 lbs per gallon, while diesel is near 7.0. On a 20-gallon fill, that gap adds up to almost 16 pounds, and on a 100-gallon transfer tank it is about 80 pounds.
Does a fuel weight calculator need temperature?
For small amounts, the effect is minor. For large loads or propane, it matters. Diesel changes about 0.5% in weight per 10°F for the same volume, while propane changes about 1.5% per 10°F. On a 9,000-gallon tanker of diesel, a swing from 30°F to 90°F moves the load by roughly 1,700 pounds. Set the fuel condition to match the actual fuel, not the air.
How much does a full 100-gallon diesel transfer tank weigh?
The diesel alone weighs about 700 lbs at 60°F. Add the empty tank and pump, which the calculator does not include. That full load counts against your truck’s payload rating, so check the door jamb sticker before filling. A pickup rated for 1,500 lbs of payload has less than 800 lbs left for people and cargo once the tank is full.
How many pounds is a gallon of Jet A?
The FAA planning value is about 6.7 lbs per US gallon. ASTM D1655 allows 775 to 840 kg/m³ at 15°C, or about 6.47 to 7.01 lbs per gallon. Operators who know the actual density from the fuel truck ticket can enter it directly for a closer figure. Avgas is lighter at 6 lbs per gallon.