| Quantity | Significance | Value* |
|---|
| Hubble constant, H0 | Present-day expansion rate of the universe |  km/s/Mpc |
| Density parameter, Ω0 | Combined mass density of all forms of matter and energy in the universe divided by the critical density | 1.02 ± 0.02 |
| Matter density parameter, Ωm | Combined mass density of all forms of matter in the universe, divided by the critical density | 0.241 ± 0.034 |
| Density parameter for ordinary matter, Ωb | Mass density of ordinary atomic matter in the universe divided by the critical density | 0.0416 ± 0.001 |
| Dark energy density parameter, ΩΛ | Mass density of dark energy in the universe divided by the critical density | 0.759 ± 0.034 |
| Age of the universe, T0 | Elapsed time from the Big Bang to the present day |  × 1010 years |
| Age of the universe at the time of recombination | Elapsed time from the Big Bang to when the universe became transparent, releasing the cosmic background radiation |  × 105 years |
| Redshift z at the time of recombination | Since the cosmic background radiation was released, the universe has expanded by a factor 1 + z | 1089 ± 1 |
| *Values for H0, Ωm, Ωb, and T0 are based on the three-year WMAP data with the assumption of a flat universe. Values for the time and redshift of recombination and for Ω0 are from the first-year WMAP data. (NASA/WMAP Science Team) |