Constants & Units · constant
Hubble constant (Planck 2018, CMB)
H₀ = 67.4 ± 0.5 km s⁻¹ Mpc⁻¹
- Unit
- km s⁻¹ Mpc⁻¹
- Value
- 67.4 ± 0.5
- Exact
- no
- Note
- Inferred from the microwave background assuming ΛCDM. Disagrees with the distance-ladder value below by ~5σ — the Hubble tension.
- Symbol
- H₀
- Category
- Cosmological
- Numeric
- 67.4
- Uncertainty
- ±0.5 (early-universe route)
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