What this calculator shows
The calculator multiplies a planned flight duration by a fuel burn rate, then adds a reserve figure computed the same way. The result is total fuel required in US gallons: trip fuel plus reserve fuel.
It answers the planning question "how much fuel does this leg need at the expected burn rate." Whether that amount satisfies a fuel requirement is a separate check, described below.
How to use the calculator
Enter three values and the results update as you type. The page URL mirrors the inputs, so a configured calculation can be bookmarked or shared.
Planned duration. The time you expect to fly at the entered burn rate, in hours, up to 24. For a cross-country leg this is the estimated time en route from your nav log.
Fuel burn rate. Gallons per hour, up to 100. Take this from the cruise performance table in the aircraft's POH for the planned altitude, power setting, and mixture technique. The same airplane can burn 8 gal/hr leaned at one setting and 11 gal/hr at another.
Planned reserve. Additional flight time to hold in reserve, in minutes, up to 180. The reserve uses the same burn rate as the trip.
How the calculation works
Trip fuel equals duration multiplied by burn rate. Reserve fuel equals the reserve minutes divided by 60 and multiplied by the same burn rate. Total fuel is the sum.
total fuel = (duration + reserve / 60) × burn rate
The model is linear and assumes one burn rate for the whole flight. Real flights burn more during climb and less during descent, so the single-rate assumption is the main source of error on long legs.
Example calculation
A 2.5 hr leg at 8.4 gal/hr with a 45 min reserve.
- Trip fuel:
2.5 × 8.4 = 21.0 gal. - Reserve fuel:
(45 / 60) × 8.4 = 6.3 gal. - Total fuel required:
21.0 + 6.3 = 27.3 gal.
When pilots use it
Cross-country planning. Estimate fuel for each leg and compare the total against usable fuel and planned fuel stops.
Reserve checks. VFR fuel minimums are 30 minutes of flight at normal cruise speed by day and 45 minutes by night under 14 CFR 91.151. Enter the applicable minutes to see what a reserve costs in gallons. The tool computes a quantity; it does not determine whether a fuel load satisfies the regulation.
Training and budgeting. Comparing duration and rate combinations shows how sensitive the total is to a small change in burn rate, which matters when a POH offers several power settings.
Assumptions and limitations
The calculation assumes a constant burn rate and does not include taxi, runup, or climb fuel, which many operators add as a fixed amount from the POH. It does not account for wind (wind changes duration, not rate), unusable fuel, fuel system behavior, or weight.
Results are in US gallons, matching how most light-aircraft fuel systems and POH tables express quantity. Avgas weighs about 6 lb per gallon, so a 30 gal total is roughly 180 lb for weight and balance purposes.
Fuel on board is verified on the aircraft, not on a screen. Gauges, fueling records, and a visual check remain the authority.
Frequently asked questions
Where do I find the burn rate?
In the POH cruise performance or range and endurance tables for the planned altitude and power setting. Engine monitors and fuel-flow instruments can provide a measured rate for a specific airplane.
Does the total include taxi fuel?
No. Taxi, runup, and climb fuel are commonly added as a fixed allowance from the POH, often around 1 gal for small trainers. Add it to the computed total if your planning counts it.
Is the reserve the same as the legal minimum?
The reserve minutes are yours to enter. Regulations define minimums, such as the VFR day and night figures above, and IFR flight carries its own fuel rules. The calculator applies whatever number you give it.
Gallons or pounds?
US gallons. For pounds, multiply gallons by about 6 for avgas or 6.7 for Jet A.
Sources and methodology
The arithmetic is duration multiplied by rate with a fractional-hour reserve, matching the fuel-planning method taught in FAA handbooks. Fuel minimums referenced above come from 14 CFR 91.151. The aircraft's POH or AFM is the authority for burn rates, usable fuel, and required margins.
Related tools and resources
Flight planning
About this site
Related glossary terms
Glossary
Squawk 7700 is the transponder code used to indicate an emergency when no more specific code or instruction applies.
Glossary
Above ground level, or AGL, is an altitude measured from the surface directly below an aircraft. Learn how it differs from MSL.
Glossary
Automatic terminal information service, or ATIS, is a recorded airport broadcast of current weather and operational information.
Directory resources
Directory
FBO directory at selected US airports
Sourced FBO listings at selected airports, with questions to confirm directly with each operator.
Directory
A&P and IA aircraft mechanic directory
How to compare aircraft mechanic and repair-station listings, confirm credentials, and evaluate maintenance services.