Fuel Planning Calculator

Just cruise fuel. The calculator multiplies your contingency percentage (5% by default, matching ICAO practice) against cruiseFuel alone, not against taxi fuel, climb fuel, or the trip-fuel total. That means a flight with a long climb or heavy taxi fuel gets proportionally less contingency cushion than the trip-fuel figure alone might suggest — the buffer is sized to protect the cruise leg specifically, since that's where a stronger-than-forecast headwind or a routing change would eat extra fuel.

PNR distance is (fuel on board minus taxi fuel minus reserve fuel) times ground speed, divided by twice the burn rate. Dividing by 2× burn rate is what makes it symmetric — it assumes the return leg burns fuel at the same rate and covers the same distance as the outbound leg, so the fuel remaining at the turnaround point is just enough to fly back. Real winds are rarely symmetric between outbound and return, so treat this PNR as a planning estimate, not a certified critical-point calculation.

The calculator defaults reserveMinutes to 45 because that covers both VFR night and IFR operations under FAR 91.151/91.167, which are the more restrictive cases. If you're flying VFR during the day, FAR 91.151 only requires a 30-minute reserve, so you can lower the Reserve Time input to 30 and the reserveFuel = (reserveMinutes ÷ 60) × burn rate calculation will shrink Total Fuel Required accordingly.

Cruise time is computed as distance ÷ ground speed, and cruise fuel is cruise time × burn rate — so a wind-uncorrected airspeed will overstate ground speed into a headwind (understating trip fuel and total required) or understate it in a tailwind (overstating fuel needed). Run your true airspeed and wind through the Wind Triangle calculator first to get an actual ground speed, then enter that here so the fuel burn matches how long you'll really be airborne.