Learn how to calculate fuel in a flight simulator, add reserves, convert units, load tanks and fix common refuelling problems.
To calculate fuel in a flight simulator, add taxi, trip, contingency, alternate and final-reserve fuel to get block fuel, then load that amount through the simulator’s weight-and-balance screen, EFB or aircraft fuel panel. Use the aircraft’s own loader for complex add-ons, and never confuse volume, mass or usable tank capacity.
The same method applies across Microsoft Flight Simulator, X-Plane, Prepar3D, FSX and similar civil simulators. The controls differ, but the planning terms and common mistakes are much the same.
What fuel amount should I load?
Load block fuel, which is the total fuel required at the departure stand before engine start and taxi.
Block fuel = taxi + trip + contingency + alternate + final reserve + additional fuel
| Fuel component | What it covers |
|---|---|
| Taxi fuel | Engine start, APU use where applicable, taxi and expected ground delays before take-off. |
| Trip fuel | Take-off, climb, cruise, descent, approach and landing at the destination. |
| Contingency fuel | Unexpected variations in winds, routing, performance or consumption. |
| Alternate fuel | A missed approach or diversion from the destination to the planned alternate, according to the planning method used. |
| Final reserve | Protected reserve that should still be onboard after the planned flight or diversion. |
| Additional or extra fuel | Known holding, weather, traffic, de-icing, extended taxi or other operational needs. |
Trip fuel is not block fuel. Loading only the trip figure omits taxi and reserves, a mistake we see constantly. Take-off fuel is normally block fuel minus the amount used before take-off.
Capacity also needs checking. A tank’s total capacity may include fuel the aircraft cannot feed to its engines, so use the model’s usable figure where it distinguishes the two; our explanation of usable, unusable and reserve fuel covers that distinction.
How do I calculate block fuel?
Calculate block fuel from the exact aircraft variant, payload, route, forecast winds and planned reserve policy rather than copying a figure from a different flight.
- Select the correct aircraft profile. Engine type, airframe variant and add-on configuration can materially change fuel burn. Enter the intended payload as well, because a heavier aircraft normally consumes more fuel.
- Estimate trip fuel by flight phase. For a light aircraft, a basic calculation is
climb fuel + (cruise time × cruise fuel flow) + descent and approach fuel. If fuel flow is quoted per engine, multiply it by the number of operating engines. Airliner calculations should account for the complete route, levels, speeds and winds. - Add taxi and reserves. Include contingency, alternate, final reserve and any known holding or delay. Check whether APU and taxi consumption are already included before adding them again.
- Check capacity and weight limits. Block fuel must fit within usable tank capacity without pushing the aircraft beyond its ramp, take-off or landing mass limits. Adjust payload, fuel stop or route if it does not.
- Review the predicted landing fuel. It should leave the planned reserves intact when the flight proceeds normally.
Worked fuel calculation
A simple example might contain 50 kg taxi fuel, 420 kg trip fuel, 25 kg contingency, 90 kg alternate fuel, 120 kg final reserve and 45 kg additional fuel.
50 + 420 + 25 + 90 + 120 + 45 = 750 kg block fuel
You would load 750 kg at the stand, not 420 kg. Expected take-off fuel would be 700 kg after taxi, and predicted destination fuel would be 280 kg if the flight used exactly the planned trip fuel. These figures illustrate the arithmetic only; they are not recommendations for a particular aircraft.
For detailed airliner planning, our SimBrief planning walkthrough explains aircraft profiles, payload, trip fuel, reserves and block fuel. If a dispatch plan already gives block fuel, do not add all its reserve components a second time.
How do I convert kilograms, pounds, litres and gallons?
Convert mass and volume separately, using the fuel’s density only when moving between those two types of measurement.
kg = lb ÷ 2.20462lb = kg × 2.20462litres = US gallons × 3.78541US gallons = litres ÷ 3.78541fuel mass = fuel volume × density
Common planning approximations are about 0.80 kg per litre for Jet A and 0.72 kg per litre for aviation gasoline, but density changes with fuel specification and temperature. A simulator or add-on may use a fixed value, so prefer the conversion displayed by its own loader. Never enter 750 gallons when the field expects 750 pounds.
How do I refuel the aircraft?
Refuel through the loading system that controls the aircraft’s fuel state, then verify the resulting quantity on both the loading page and cockpit gauges.
| Refuelling method | Choose it when | Main caveat |
|---|---|---|
| Simulator fuel or weight-and-balance menu | Using default aircraft or making an instant fuel change | It may be overridden by a complex add-on’s custom systems. |
| Aircraft EFB, tablet or loading panel | Flying a detailed airliner or other system-heavy add-on | This is usually the preferred method; loading may take time rather than happen instantly. |
| Ground-service fuel truck | Simulating a normal turnaround at a parking stand | The airport, aircraft and ground-service system must support fuel delivery. |
Microsoft Flight Simulator 2024 users can plan and review loading through the tools described in our guide to the EFB’s route, fuel and payload functions. For a truck-based turnaround, follow the MSFS 2024 ground-service refuelling procedure.
- Park and secure the aircraft. Set the parking brake and shut down the engines if the selected aircraft or service requires it.
- Read the fuel already onboard. This matters when the loader asks for an uplift rather than a final quantity.
- Open the correct loading system. Use the aircraft’s EFB or custom panel when its documentation specifies one; otherwise use the simulator’s fuel or weight-and-balance page.
- Enter the requested value carefully. A target of 750 kg means the aircraft should finish with 750 kg onboard. If it already contains 200 kg and the interface asks for uplift, request 550 kg instead.
- Distribute fuel by tank. Follow the aircraft’s prescribed loading sequence. If entering tank quantities manually, keep paired wing tanks balanced unless the aircraft specifically requires another arrangement.
- Apply the load and verify it. Confirm total fuel, tank balance, gross mass and centre of gravity. Detailed aircraft may require electrical power, an open refuelling panel or a waiting period while fuel transfers.
Why will the aircraft not refuel?
When refuelling fails, the usual cause is a conflict between the simulator’s loading menu and the aircraft’s custom fuel system.
- The fuel value snaps back: the add-on is controlling fuel independently. Set the quantity through its EFB, tablet, FMS utility or loading panel.
- The truck arrives but no fuel transfers: confirm the parking brake is set, engines are shut down if required, the aircraft is at a suitable stand and its ground-service integration supports refuelling.
- The quantity is wildly wrong: recheck kilograms against pounds and litres against US gallons. Also determine whether the box expects a per-tank figure, total onboard fuel or uplift.
- The total is correct but the aircraft lists: fuel has been loaded asymmetrically. Correct the individual tank quantities before departure.
- The engines stop with fuel remaining: check tank selectors, pumps, crossfeed, mixture or condition levers. Fuel in an unselected tank is not available to the engine, and some aircraft model unusable fuel.
- Fuel never decreases: disable unlimited-fuel or fuel-assistance settings and check whether the aircraft has entered a saved or failed state.
Why is fuel burn higher than planned?
Fuel burn usually exceeds the plan because the aircraft profile, weather, altitude, speed, payload or engine settings do not match the assumptions used for the calculation.
For piston aircraft, an over-rich mixture at altitude and excessive power are common causes. For jets, low-level cruise, unexpected headwinds, prolonged anti-ice use, holding, APU operation and high-speed flight all increase consumption. Compare remaining fuel with the planned figure after climb; a growing shortfall means the flight plan or operating technique needs correction.
How much reserve fuel should I carry?
There is no universal reserve figure for every simulator flight, aircraft and operating rule.
For casual simulation, carry enough for plausible delays and a diversion rather than planning to arrive nearly empty. When recreating real operations, apply the appropriate VFR, IFR or airline planning policy for the scenario and protect the final reserve instead of treating it as ordinary trip fuel. Simulator estimates and generic examples should never be used for real-world flight planning.