How Much Does the Universe Weigh? A Bold Attempt to Weigh Everything That Exists

When we talk about weight, we usually think of something tangible an apple, a car, maybe even a skyscraper. But what if we try to measure something truly colossal? What if we dared to ask: How much does everything weigh? Stars, planets, black holes, dark matter even light. In short: how much does the universe weigh?

Let’s explore how scientists are attempting to weigh the unimaginable.

What Does the “Weight” of the Universe Even Mean?

First, a little clarification. In physics, weight is the force an object feels due to gravity. Mass, on the other hand, is the amount of matter an object contains, independent of gravity. So when scientists talk about the “weight” of the universe, they’re really referring to its mass.

But here’s the challenge: most of the universe is invisible. We can’t just put galaxies on a giant cosmic scale. Instead, scientists have to get creative.

How Do You Weigh a Universe?

Astrophysicists use several clever methods to estimate the universe’s total mass. Here are the three most important:

1. Watching How Galaxies Move

Galaxies spin. If they were made only of visible matter stars, gas, and dust they would rotate much slower. But they don’t. The fact that they spin so quickly tells us something unseen is adding extra mass. That mysterious “stuff” is what we call dark matter and it far outweighs all visible matter.

2. Gravitational Lensing: Nature’s Magnifying Glass

Mass bends light. This isn’t sci-fi it’s a real effect predicted by Einstein’s theory of relativity. When light from distant galaxies passes near a massive object (like a galaxy cluster), it gets bent, just like light passing through a lens. By analyzing how much the light is distorted, scientists can estimate the mass causing the bend including the invisible parts.

3. Listening to the Echo of the Big Bang

The cosmic microwave background (CMB) is the oldest light in the universe — a relic of the Big Bang. Tiny fluctuations in this ancient radiation help scientists determine the density of matter in the early universe, which allows them to model how much mass there is today.

So... How Much Does It All Weigh?

The current best estimate for the mass of the observable universe is about:

10⁵³ kilograms.

Let that sink in.

For comparison, Earth weighs about 6×10²⁴ kilograms. That means the universe is around 10²⁹ times heavier than our planet. A number so enormous it stretches the limits of human imagination.

What Contributes to This Massive Mass?

Here’s a rough breakdown of what makes up that weight:

• Ordinary Matter (a.k.a. Baryonic Matter): ~5%

This includes everything we can see — stars, planets, gas clouds, even us. Shockingly, it accounts for just a tiny fraction of the universe’s mass.

• Dark Matter: ~27%

It doesn’t emit light, doesn’t interact with electromagnetic forces, and we can’t see it directly — but it exerts gravity. It’s the invisible framework holding galaxies together.

• Dark Energy: ~68%

This mysterious force is driving the universe’s accelerated expansion. While it’s not “mass” in the traditional sense, it carries energy — and thanks to Einstein’s equation E=mc², energy has mass. So it contributes significantly to the universe’s total “weight.”

Wait — Does Light Have Mass?

Photons, the particles of light, have no rest mass. But they do carry energy and by Einstein’s theory, energy is equivalent to mass. So yes, even light adds a little weight to the universe. It’s not much, but in a universe this size, even “not much” adds up.

What If the Universe Is Infinite?

That’s the wild card. If the universe is infinite and some theories suggest it might be then its total mass would also be infinite. But when scientists refer to the “mass of the universe,” they’re usually talking about the observable universe the part of the cosmos we can actually see, limited by how far light has traveled since the Big Bang.

This visible bubble has a diameter of about 93 billion light-years. Everything beyond that is currently out of reach both for our telescopes and our scales.

Why Bother Weighing the Universe?

Knowing the mass of the universe helps scientists:

• Predict its future — will it expand forever, slow down, or collapse in on itself?
• Understand how galaxies formed and evolved.
• Test and refine models of cosmology, gravity, and dark energy.

And on a philosophical level, measuring the universe is a reminder of our place in it a tiny speck of dust in a cosmos weighing 10⁵³ kilograms.

Final Thoughts

Weighing the universe is a monumental task one that combines astronomy, physics, mathematics, and imagination. It's not just a matter of numbers; it's a journey toward understanding everything that exists.

And while the true mass of the cosmos might still be uncertain, the fact that we can even ask this question and begin to answer it is a stunning testament to human curiosity and intellect.