Trip fuel plus reserve minus fuel onboard.
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Fuel tool
Fuel Stop Budget Calculator
Estimate gallons to buy after accounting for tank level, reserve, MPG, and trip miles.
Use this whenUse it when you know the trip miles and want a safe fuel-buy number without overfilling.
Fuel stop budget
Estimate how much to buy while protecting your reserve.
Gallons to buy times diesel price.
Trip miles divided by MPG.
Budget logic
Buy only what the trip and reserve require.
trip gallons + reserve gallons - onboard gallonsThis is a budgeting helper. Actual routing, taxes, discounts, and fuel-network rules still matter.
Practical use
Useful before expensive-state fuel stops.
Run the calculator before entering a high-price market so you know whether a partial buy is enough.