Critical Density of the Universe
| Value | 8.53 × 10⁻²⁷ kg/m³ |
| Status | Measured: ± 1.3 × 10⁻²⁸ kg/m³ (1.5 % relative), standard uncertainty |
| Source | Derived from the Planck 2018 H₀ and CODATA 2022 G |
| Categories | Astronomical |
| Unit | Value |
|---|---|
| kilogram per cubic meter | 8.5300000e-27 kg/m³ |
15 more density units
| microgram per liter | 8.5300000e-21 μg/L |
| milligram per cubic meter | 8.5300000e-21 mg/m³ |
| milligram per liter | 8.5300000e-24 mg/L |
| pound per cubic yard | 1.4377784e-26 lb/yd³ |
| gram per liter | 8.5300000e-27 g/L |
| pound per cubic foot | 5.3251050e-28 lb/ft³ |
| pound per imperial gallon | 8.5491182e-29 lb/imp gal |
| pound per US gallon | 7.1186300e-29 lb/gal |
| slug per cubic foot | 1.6550932e-29 slug/ft³ |
| gram per cubic centimeter | 8.5300000e-30 g/cm³ |
| gram per milliliter | 8.5300000e-30 g/mL |
| kilogram per liter | 8.5300000e-30 kg/L |
| tonne per cubic meter | 8.5300000e-30 t/m³ |
| US short ton per cubic yard | 7.1888918e-30 ton/yd³ |
| pound per cubic inch | 3.0816580e-31 lb/in³ |
Learning zone
The critical density is the dividing line in Friedmann's equations between a universe that expands forever and one that recollapses, and it is absurdly small: five hydrogen atoms in a cubic metre, a vacuum far better than any laboratory can produce. Measurements of the microwave background show the universe sits at that value to within a fraction of a per cent, so space is flat on the largest scales, which is what the theory of inflation predicts.
What supplies the density is the surprise. Ordinary atoms account for only about 5 per cent of it, dark matter for 27 per cent, and dark energy for the remaining 68 per cent. The value scales as H₀², so it inherits the Hubble tension: pick the distance-ladder H₀ instead of the microwave-background one and the critical density rises by about 17 per cent.
Cite this page
formula.expert. (2026, October 16). Critical Density of the Universe. https://formula.expert/constants/critical-density-universe