Measured quantity · Cosmology
The Hubble Constant
Cosmology & UniverseEstablished Science
Definition
The present-day rate of expansion of the Universe, denoted H₀.
Scientific overview
The Hubble constant sets the current expansion rate and, with it, the scale and age of the Universe. It is measured in kilometres per second per megaparsec.
Current measurements
| From the CMB (early Universe) | 67.4 ± 0.5 km/s/Mpc | Planck Collaboration |
| From the local distance ladder | ≈ 73 km/s/MpcSH0ES / Cepheid + Type Ia supernovae | NASA |
Measured by
Related topics
Knowledge connections
- Related toThe Expansion of the Universe
- Related toThe Hubble–Lemaître Law
- Related toThe Hubble–Lemaître Law
- Related toThe Hubble Tension
- Related toThe Expansion of the Universe
- Measured byPlanck
- Measured byHubble Space Telescope
- Measured byDESI (Dark Energy Spectroscopic Instrument)
- Related toThe Hubble Tension
- Required byThe Age of the Universe
- Associated withRedshift & the Hubble–Lemaître Law
- Associated withThe Cosmic Distance Ladder
- Associated withTip of the Red Giant Branch
- Associated withWater Megamaser Distances
- Associated withStandard Sirens
- Associated withSH0ES
- Associated withHubble Distance
Sources & references
The primary and reference sources this topic draws on.
- Planck CollaborationESA Planck mission / Planck Collaboration
Cosmic microwave background maps and the cosmological parameters of the ΛCDM model.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.