Fuel Calculation Quick Reference

Running out of fuel ranks among the most preventable causes of aviation accidents. A simple fuel calculation process, performed before every flight, eliminates this risk entirely.

The Basic Formula

Total fuel minus reserve minus taxi equals usable trip fuel. Divide by fuel burn rate to get endurance. Compare against planned flight time plus contingency.

Example: 40 gallons onboard, 8 GPH burn rate, 45-minute VFR reserve requirement. Taxi uses 1 gallon. That’s 40 – 6 – 1 = 33 gallons for the trip, or about 4 hours of flight time.

Know Your Aircraft

Use actual fuel burn figures from your logbook, not book numbers. Most aircraft burn more than POH estimates, especially in climb. A Cessna 172 might show 8.5 GPH book, but actually burn 9-10 in real operations.

The Visual Check

Never trust gauges alone. Visually verify fuel quantity during preflight. Many gauges are notoriously inaccurate, especially at low fuel states. When in doubt, stick the tanks.

Build in Margin

VFR requires 30 minutes reserve (day) or 45 minutes (night). IFR requires 45 minutes. Smart pilots plan for more—weather changes, headwinds, diversions, and holding all consume fuel faster than expected.

The Landing Rule

Always know exactly how much fuel you have remaining at every landing. Log it. Track it. A pilot who can’t tell you their current fuel state has already made one mistake too many.

Fuel planning takes five minutes. Running dry takes forever to explain.