James Webb Space Telescope
The James Webb Space Telescope is an infrared observatory in space designed to study distant galaxies, stars and planetary systems.
Also known as: JWST, Webb telescope
How big is it?
21.2 m long
Deployed sunshield length · specified
A little perspective
About the same scale as Doubles tennis court.
Doubles tennis court: A doubles tennis court is the marked playing surface used for tennis with the outer doubles sidelines included.
Measurements, assumptions & sources +
James Webb Space Telescope
JWST’s deployed observatory spans about 21.2 m by 14.2 m across its sunshield and has a mass of approximately 6,200 kg. The long sunshield axis is the default scale span.
The marked deployed sunshield length is calibrated. Unmeasured illustration details are representative.
Doubles tennis court
23.77 × 10.97 m playing surface. Excludes surrounding space.
The marked length is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 21.2 m
For comparison, this page uses deployed sunshield length. The record labels this value specified, so the stated convention rather than an inferred average controls the comparison.
JWST’s deployed observatory spans about 21.2 m by 14.2 m across its sunshield and has a mass of approximately 6,200 kg. The long sunshield axis is the default scale span.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
James Webb Space Telescope dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 21.2 m | Not recorded | specified | |
| 14.2 m | Not recorded | specified | |
| 6.2 t | Not recorded | specified |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · SpaceJuno spacecraft20 mJuno is a NASA spacecraft sent to study Jupiter’s atmosphere, magnetic field and structure, powered by three large solar arrays.
Around the same scale · SportBaseball batting cage21.3 mA baseball batting cage is a netted enclosure used for practising batting, allowing players to hit balls safely without risk of them travelling far or causing injury.
Nearest higher value · SpaceSkylab36.1 mSkylab was the first American space station, used for scientific experiments and crewed missions in Earth orbit during the 1970s.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NASA — Webb fact sheetDeployed sunshield dimensions and observatory mass.
There’s always another scale
Follow your curiosity.
SpaceHubble Space Telescope13.2 mThe Hubble Space Telescope is an orbiting observatory launched by NASA to capture detailed images of astronomical objects.SpaceSkylab36.1 mSkylab was the first American space station, used for scientific experiments and crewed missions in Earth orbit during the 1970s.
SportDoubles tennis court23.77 mA doubles tennis court is the marked playing surface used for tennis with the outer doubles sidelines included.SpaceJuno spacecraft20 mJuno is a NASA spacecraft sent to study Jupiter’s atmosphere, magnetic field and structure, powered by three large solar arrays.
Living thingsBlue whale25 mA blue whale is a baleen whale that feeds by filtering small animals from seawater.
TransportCanal narrowboat17.7 mA canal narrowboat is a long, slender vessel designed for navigating the narrow canals of the United Kingdom.
SportSingles tennis court23.77 mA singles tennis court is a rectangular surface with marked lines used for playing one-on-one tennis matches.
Everyday things10 × 20 m garden20 mA garden is an outdoor space where people cultivate plants, flowers or vegetables for pleasure, relaxation or food.