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 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 cannot reach orbit without a full fuel load. For this reason the related term propellant 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 Payload 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 2.506%
SpaceX Starship (vehicle + payload) 4,400,000 kg (9,700,000 lb) [2] 85,000 kg (187,000 lb)[2] + 100,000 kg (220,000 lb)[3] 18.7 5.341%
SpaceX Starship (payload only) 4,400,000 kg (9,700,000 lb) [2] 100,000 kg (220,000 lb)[3] 29.3 3.409%
Soyuz-2.1b 312,000 kg 8,200 kg[4] 38.05 2.63%
Soyuz-2.1a 312,000 kg 7,020 kg[4] 44.444 2.25%
Saturn V 3,038,500 kg[5] (~6,700,000 lb) 13,300 kg + 118,000 kg[5] (~29,320 lb + ~260,150 lb) 23.1 4.33%
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 6.49%
Space Shuttle (payload only) 2,040,000 kg (~4,500,000 lb) 28,800 kg (~230,000 lb + ~63,500 lb) 70.83 1.41%
Skylon (vehicle + payload) - projected 345 tons [6] 15 + 53 5.07 19.71%
Skylon (payload) - projected 345 tons[6] 15 23 4.35%
Saturn 1B (stage only) 448,648 kg[7] (989,100 lb) 41,594 kg[7] (91,700 lb) 10.7 9.346%
Titan 23G first stage 117,020 kg (258,000 lb) 4,760 kg (10,500 lb) 24.6 4.065%
Virgin Atlantic GlobalFlyer 10,024.39 kg (22,100 lb) 1,678.3 kg (3,700 lb) 6.0 16.66%
V-2 13,000 kg (~28,660 lb) (12.8 ton) 3.85 25.97% [8]
X-15 15,420 kg (34,000 lb) 6,620 kg (14,600 lb) 2.3 43.478%[9]
Concorde ~181,000 kg (400,000 lb [9]) 2 50%[9]
Boeing 747 ~363,000 kg (800,000 lb[9]) 2 50%[9]
Lunar Module Descent stage 15,200 kg [10] 6,845 kg 2.22 45.03%[10]
Lunar Module Ascent stage 4,780 kg [10] 2405 kg 1.9875 50.31%[10]

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