I think that Total mass of universe can be calculated using below formula.

Total mass of universe = (Age of Universe) × (Planck mass / Planck time)

= (4.35×10^17 ) × (2.18×10 ^−8 / 5.39×10^−44 ) Kg

= 1.75×10^53 Kg

Which matches the current predictions to great extents. Would like to see your feedback about this.

I have heard of some overall mass density.

You know the universe expands at speed

V=Hr , r is radius. So accelerating out

At a=Hv=HHr

Then you have to assume gravity is an inertial reaction to this effect.

So Fg on m due whole universe=ma

And you eventully get an answer for

rho average density.

The total mass of the universe is calculated using a combination of observations and theoretical models, integrating contributions from different components:

1. Ordinary (Baryonic) Matter: This includes stars, galaxies, gas clouds, and other visible matter. The mass of ordinary matter is estimated from observations of luminous objects and the density of gas in interstellar and intergalactic space.

2. Dark Matter: Dark matter does not emit light, but its presence is inferred from its gravitational effects on visible matter, such as the rotational speeds of galaxies and gravitational lensing. Dark matter is believed to make up a significant portion of the total mass of the universe, far more than ordinary matter.

3. Dark Energy: While not mass in the traditional sense, dark energy contributes to the universe's total energy density and affects the expansion of the universe. It's responsible for the accelerated expansion observed in distant galaxies.

4. Cosmological Measurements: The total mass of the universe is often expressed in terms of the critical density; which is the density required for the universe to be flat (in terms of general relativity). The total mass-energy of the universe is compared to this critical density.

The density parameter \( \Omega \) is a key measure:

- \( \Omega_m \): This represents the fraction of the critical density contributed by matter (both dark and ordinary).

- \( \Omega_\Lambda \): This represents the fraction of the critical density from dark energy.

Observations, particularly from the Cosmic Microwave Background (CMB) radiation (such as from the Planck satellite), allow cosmologists to estimate these densities. The current estimate suggests that the universe consists of approximately:

- 5% ordinary matter

- 27% dark matter

- 68% dark energy

By combining these components, scientists estimate the universe’s total mass. In practice, the universe’s mass-energy is calculated in terms of a combination of mass (for matter) and energy (for dark energy and radiation), since energy and mass are equivalent through Einstein's equation \( E = mc^2 \).

These methods rely heavily on observational data, including galaxy rotation curves, large-scale structure surveys, supernova measurements, and the CMB, which together provide a comprehensive estimate of the universe's total mass-energy content.