In aerospace engineering, payload fraction is a common term used to characterize the efficiency of a particular design. Payload fraction is calculated by dividing the weight of the payload by the takeoff weight of aircraft. Fuel represents a considerable amount of the overall takeoff weight, and for shorter trips it is quite common to load less fuel in order to carry a lighter load. For this reason the useful load fraction calculates a similar number, but based on the combined weight of the payload and fuel together.

Propeller-driven airliners had useful load fractions on the order of 25-35%. Modern jet-powered airliners have considerably higher useful load fractions, on the order of 45-55%.

For spacecraft the payload fraction is often less than 1%, while the useful load fraction is perhaps 90%. In this case the useful load fraction is not a useful term, because spacecraft typically can't reach orbit without a full fuel load. For this reason the related term mass fraction, is used instead. However, if the latter is large, the payload can only be small.

## Examples

Vehicle Takeoff Mass Final Mass Mass ratio Mass fraction
Ariane 5 (vehicle + payload) 746,000 kg [1] (~1,645,000 lb) 2,700 kg + 16,000 kg[1] (~6,000 lb + ~35,300 lb) 39.9 0.975
Titan 23G first stage 117,020 kg (258,000 lb) 4,760 kg (10,500 lb) 24.6 0.959
Saturn V 3,038,500 kg[2] (~6,700,000 lb) 13,300 kg + 118,000 kg[2] (~29,320 lb + ~260,150 lb) 23.1 0.957
Space Shuttle (vehicle + payload) 2,040,000 kg (~4,500,000 lb) 104,000 kg + 28,800 kg (~230,000 lb + ~63,500 lb) 15.4 0.935
Saturn 1B (stage only) 448,648 kg[3] (989,100 lb) 41,594 kg[3] (91,700 lb) 10.7 0.907
Virgin Atlantic GlobalFlyer 10,024.39 kg (22,100 lb) 1,678.3 kg (3,700 lb) 6.0 0.83
V-2 13,000 kg (~28,660 lb) (12.8 ton) 3.85 0.74 [4]
X-15 15,420 kg (34,000 lb) 6,620 kg (14,600 lb) 2.3 0.57[5]
Concorde ~181,000 kg (400,000 lb [5]) 2 0.5[5]
Boeing 747 ~363,000 kg (800,000 lb[5]) 2 0.5[5]

Note: the above table may incorrectly include the mass of the empty upper stage or stages.