Useful Load Calculator
Find your aircraft's useful load and how much payload remains after fuel. Enter the weights from your specific aircraft's documentation.
Aircraft Weights
From the POH/AFM for your aircraft.
From the signed weight-and-balance record.
Fuel
Load
Understanding useful load
Every aircraft has a fixed maximum approved weight set by the manufacturer and a basic empty weight recorded for that specific airframe. The difference between them — the useful load — is everything you are allowed to add: usable fuel, the pilot and passengers, baggage, and cargo. Because fuel and payload compete for the same useful load, a full-fuel departure often leaves little capacity for people and bags, and a full-seats departure may require reduced fuel and an added stop.
This calculator makes that trade-off explicit so you can plan a legal, safe load. Enter your real numbers from the aircraft's paperwork — do not rely on generic model figures, which vary with installed avionics and equipment.
This calculator is for planning only and does not verify center of gravity. Always use your aircraft's current weight-and-balance data and POH/AFM limits, and confirm both weight and CG before every flight. Read our full Safety Disclaimer.
Frequently Asked Questions
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OpenUseful Load in Depth
Useful load is the difference between an aircraft's maximum gross weight and its empty weight — the total weight of everything you are allowed to add, including fuel, occupants, and baggage. It is the number that ultimately decides how many people and how much fuel you can carry on a given flight, and it is the starting point for any realistic trip-planning conversation about payload versus range.
The crucial insight useful load reveals is the trade-off between fuel and payload. Because fuel is heavy, filling the tanks consumes a large share of the useful load, leaving less for people and bags. A pilot who understands useful load knows that full tanks and full seats are often mutually exclusive in a light aircraft, and plans the flight around that reality rather than discovering it on the ramp.
Step-by-Step: How the Calculation Works
Useful load equals maximum gross weight minus the empty weight from your aircraft weighing record. From that figure you subtract the weight of the fuel you intend to carry to find the payload available for occupants and baggage — or, working the other way, subtract the weight of your occupants and baggage to find how much fuel the aircraft can legally lift.
Fuel weight is the pivot of the calculation: aviation gasoline weighs about 6 pounds per gallon, so 50 gallons is roughly 300 pounds of the useful load. The calculator lets you enter empty weight, gross weight, and your intended loads to see immediately whether a desired combination fits, and how much fuel you must trade away to carry an extra passenger.
More Worked Examples
Example 1 — Full seats or full tanks
Gross weight 2,550 lb, empty weight 1,680 lb, so useful load is 870 lb. Four occupants at 680 lb and 40 lb of baggage total 720 lb, leaving 150 lb — about 25 gallons — for fuel. Full 53-gallon tanks (318 lb) would exceed the useful load with that many people aboard, so you carry either full fuel or a full cabin, not both.
Example 2 — Solo with full fuel
The same aircraft flown solo with a 190-lb pilot and 20 lb of baggage uses 210 lb of the 870-lb useful load, leaving 660 lb — far more than the tanks can hold. Full fuel is easily accommodated, and the flight is payload-limited only by having empty seats to fill.
Pilot Decision-Making Context
Useful load turns trip planning into a series of concrete trade-offs. When a full load of passengers is the priority, you accept reduced fuel and plan shorter legs with fuel stops. When maximum range matters, you carry full fuel and limit passengers or baggage. Neither choice is wrong, but pretending both can be maximized at once is how aircraft end up overweight.
The number also interacts directly with balance. Removing fuel to stay under gross weight can shift the CG, and adding baggage to use up spare useful load can push the CG aft. A complete plan checks useful load and center of gravity together, because a loading that satisfies one limit can violate the other.
More Questions Answered
Is useful load the same as payload?
Not quite. Useful load includes usable fuel plus payload. Payload is what remains for occupants and baggage after the fuel you choose to carry is subtracted from the useful load.
Why can't I always fill the tanks and the seats?
Because fuel is heavy. In many light aircraft the combined weight of full fuel and full seats exceeds the useful load, forcing a trade-off between range and payload.
Does useful load change over time?
It can. Adding equipment or repainting raises empty weight and reduces useful load, which is why the current weighing record — not the original factory figure — should be used.
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