iCosmos › Cosmic history

Cosmic history

How a universe changes over time, for the model set in the calculator's inputs.

Plots

• The Hubble parameter H(z).
• Lookback time against redshift.
• The scale factor a(t).
• The density parameters Ω_m(z), Ω_Λ(z), Ω_r(z) and Ω_k(z).
• The deceleration parameter q(z), which changes sign when the expansion begins to accelerate.
• The dark-energy equation of state w(z) = w₀ + w_a z/(1+z).

Every plot can be zoomed, read out point by point and exported. Related calculators: Hubble parameter, lookback time, age of the universe.

Open the iCosmos cosmology calculator

iCosmos 4.5.0 · updated 10 November 2026