Tank Fill-Up Cost Calculator
Enter your tank's total capacity, how full it currently is, and the price per gallon to calculate how much a fill-up will cost.
Fill-up cost
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Enter your tank details to calculate.
How the Tank Fill-Up Cost formula works
Gallons needed based on the empty portion of the tank:
Gallons needed = Tank capacity × (1 − Current fill fraction) Cost = Gallons needed × Price per gallon
Step-by-step calculation
- Subtract your current fill fraction from 1 to find the empty portion of the tank.
- Multiply by tank capacity to find gallons needed.
- Multiply by price per gallon for total fill-up cost.
Worked example
A 14-gallon tank at 1/4 full, with gas at $3.60/gallon: Gallons needed = 14 × (1 − 0.25) = 10.5 gallons. Cost = 10.5 × 3.60 = $37.80.
Frequently asked questions
Where do I find my tank's total capacity?
It's typically listed in the vehicle owner's manual, or can often be found with a quick search of your vehicle's make, model, and year.