Fuel planning and reserves for pilots
How burn rate, endurance and range fit together, why this tool excludes reserves, and how to add taxi, climb and IFR fuel by hand.
The three numbers and how they connect
Fuel planning from a burn rate rests on three linked quantities. Fuel required answers how much you will burn for a set time and comes from burn rate times flight time. Endurance answers how long a tank will last and comes from fuel onboard divided by burn rate. Range answers how far that endurance carries you and comes from endurance times groundspeed. This calculator gives you whichever of the three the inputs support, so entering flight time drives fuel required while entering fuel onboard drives endurance, and adding a groundspeed to fuel onboard unlocks range. Understanding which input feeds which output makes it easy to plan either forward from a time or backward from the fuel in the tanks.
Why the results exclude reserves on purpose
The tool deliberately reports raw burn with no safety margin baked in, because reserve rules differ by country, by operation and by whether you fly VFR or IFR. In the United States a day VFR flight must plan to land with at least 30 minutes of fuel at normal cruise, night VFR requires 45 minutes, and IFR adds fuel to reach an alternate plus 45 minutes. Those reserves are yours to add on top of the number this page shows. Treating the output as usable fuel would quietly erode your safety margin, so it is left clean and honest for you to build on.
Turning a clean burn figure into a fuel load
To build a real fuel load, start from the fuel required for your leg, then stack the extras. Add taxi and run-up fuel for the departure, add a climb allowance if your burn rate reflects cruise only, add your legal reserve, and add alternate and holding fuel when the weather or the rules call for it. For example, a leg needing 35 gallons at 10 gallons per hour might become roughly 35 plus 2 for taxi plus 5 for the reserve, landing near 42 gallons before any alternate. Endurance from the calculator is a useful cross check: if your planned block time plus reserve exceeds the endurance the tanks give, you are carrying too little fuel and need a stop.
Where the still-air range estimate breaks down
Range here assumes a constant groundspeed in still air, which is a clean model but rarely the whole story. A headwind lowers your groundspeed and shrinks range for the same fuel, while a tailwind stretches it, so on a windy day you should feed in the groundspeed you actually expect for that leg rather than your true airspeed. The climb and descent also burn and cover ground at different rates than cruise. Use the range figure to compare options and to check that a destination is plausibly within reach, then confirm the detail with a full navigation log that accounts for wind at each leg.