Convert H₀ into h
Cosmological tables often quote the dimensionless Hubble parameter:
h = H₀ / 100
h = 0.674
From model parameters to percentages
How are the cosmic percentages calculated?
The percentages on the homepage are not four direct meter readings. They are a compact representation of parameters inferred by fitting a cosmological model to observations. This page exposes the conversion from the commonly quoted physical densities ω = Ωh² to the fractional density parameters Ω.
Important: this calculator reproduces the parameter conversion and flat-universe closure arithmetic. It does not rerun the Planck likelihood, Boltzmann solver or CMB parameter inference.
Interactive reference
Change the inputs
Start from a Planck-2018-like base ΛCDM reference. Change H₀ or the physical densities and see how the fractions move.
Radiation0.01%
Ordinary matter4.9%
Cold dark matter26.4%
Dark energy / closure term68.7%
Convert physical densities
Planck-style tables quote ωb and ωcdm. The corresponding fractional densities are Ω = ω/h².
Ωb = ωb / h²
Ωcdm = ωcdm / h²
Ωr = ωr / h²
Use flat-universe closure
For the simplified flat reference used on the homepage, the remaining budget is assigned to the cosmological-constant term.
ΩΛ = 1 − Ωb − Ωcdm − Ωr
Closure check: 1.000000
Sources and provenance
Where do the fitted inputs come from?
The numerical inputs are representative of the final Planck 2018 base-ΛCDM cosmological-parameter analysis. The exact posterior values depend on the dataset combination and neutrino convention; the homepage intentionally displays rounded pedagogical buckets.