Between the highest number you can count to and infinity are many enormous numbers that are incomprehensible to the human mind: a billion, a trillion, and beyond. Here are some conversions, comparisons, and context to help you think through such massive quantities.

1.  THE SPEED OF LIGHT // 186,282 MPS

Let’s start with the speed of light—a very important constant in physics, the c in Einstein’s E=mc2. In a vacuum, the speed of light is 186,282 miles (299,792 km) per second. That’s really fast—in fact, according to the theory of special relativity, nothing in the universe is faster.

Of course, science fiction tells a different story, like warp speed, the Star Trek technology that propels starships through light-years of space. For now though, no object can travel at the speed of light, but if you could, you could go around the world 7.5 times in one second. For reference, Earth’s circumference is 24,901 miles (40,075 km). A moderately active person walking 7500 steps a day would circumnavigate the globe every 22 years. So, light can travel the same distance in one second than the average human can travel in 165 years.


Circle the planet a few more times—about 10 in total—and you’d have gone the distance to the moon: 238,855 miles (384,400 km), on average.

If you could fold a piece of paper in half 42 times—you can’t; the record is 12, but say, hypothetically, that you could—you would have a paper tower that reached to the moon.

Doesn’t sound right, does it? That’s because our brains tend to think in linear terms. Folding a piece of paper in half and half again is an example of exponential, or more specifically, geometric growth. The thickness of the piece of paper, 0.0039 inches (0.1 mm) on average, doubles with the first fold to 0.0078 inches (0.2 mm), and for the next few folds, the numbers stay small. However, by seven folds, your paper has become as thick as a notebook with 128 pages. And it keeps growing from there. Here’s a picture of what the 11th fold looks like.

And if you folded it 103 times? The paper would be thicker than the diameter of the entire known universe

3.  THE BIG BANG // 13,800,000,000 YEARS AGO

Now, we’re moving up in order of magnitude, leaving behind six figures, bypassing the millions, and continuing on to the billions. Remember, a million and a billion are vastly different—much more than that single letter change makes them look. If you won a million-dollar lottery and made it last for 50 years, you could spend $54.79 per day. But if your prize was a billion dollars, you could spend $54,794 per day.

With the bigness of billions in mind, consider the age of the universe. The Big Bang and the birth of the universe took place an estimated 13.8 billion years ago. Carl Sagan’s famous "Cosmic Calendar" idea attempts to make sense of such a number by scaling the universe’s 13.8-billion-year history to a calendar year. In this visualization, humans would only be present for the last few minutes of New Year’s Eve—and your life would last less than one-quarter of a second, or the blink of an eye.

4.  ALL THE STARS IN THE MILKY WAY // 300,000,000,000

There are few sights more awe-inspiringly uncountable than a sky full of stars on a clear, dark night. Yet even under ideal conditions, there are only between 2000 and 5000 stars visible to the naked eye. Astronomers estimate only 10,000 stars are bright enough to be seen without a telescope, and daylight falls over half the Earth at any given time, obscuring half the sky. Light pollution, hazy horizons, and individual light sensitivity all add up to most of us being unable to gaze upon more than a few thousand stars.

Within the Milky Way galaxy are 300 billion stars. That’s enough for every person on Earth to have 42 stars all to themselves, or for each household in America to have their own sky full. And besides the Milky Way, there are at least 100 billion more galaxies. According to a 2010 study led by Yale astronomer Pieter van Dokkum, some of those galaxies might contain five to 10 times the number of stars previously thought, leading to an estimate of around 300 sextillion—that’s 3 followed by 23 zeroes.

5.  THE NUMBER OF DIGITS IN PI (SO FAR) // 13,300,000,000,000

Though pi is an irrational number with infinite decimal digits, our knowledge of it is finite. Computer programs can calculate the value of pi to a precision far beyond what is scientifically necessary. Rounding pi to 3.14159 is plenty accurate for most applications, and even NASA only uses 15 or 16 digits of pi in its calculations.

But some scientists have taken on the challenge of discovering many more digits. In 2011, 10 trillion digits of pi were calculated by systems engineer Shigeru Kondo on his personal computer, using a program created by computer scientist Alexander Yee. (The 10 trillionth digit was a 5.) Yee’s program was also used to compute the current world record-setting 13.3 trillion digits of pi. That number took 208 days to compute.   

6.  THE NUMBER OF CELLS IN THE HUMAN BODY // 37,200,000,000,000

Estimating the number of cells in the human body has long posed problems for scientists. As science writer Carl Zimmer explains, "Our bodies are not packed with cells in a uniform way, like a jar full of jellybeans. Cells come in different sizes, and they grow in different densities." Simply averaging cell size and volume yielded significant inaccuracies in the calculations.

In a 2013 study, a group of European scientists overcame this problem by using a new method. They divided the human body into its various organs and cell types—separating bone marrow from red blood cells, for example. Their estimated total was a staggering 37.2 trillion cells.

Note that this study only counted the number of human cells. Each person is also home to 100 trillion microbes—meaning that your body is made up of more bacteria than cells.


This massive number, which begins with nine quintillion, is the biggest signed integer that a 64-bit processor in a modern computer can store. In the past, most computers were made with 32-bit processors, which could only store data values up to 2,147,483,647, or 2 billion and change.

Both processors sound like they can handle a lot of data, but the 32-bit isn’t enough to display dates occurring 2,147,483,647 seconds after January 1, 1970. This means 32-bit processors will experience the Year 2038 problem—something similar to what people thought would happen with Y2K—and will reset on January 19, 2038 at 3:14:07. Computers using 64-bit hardware will be fine—they can display dates for the next 292 billion years.

You may remember back in 2014 when Psy's viral "Gangnam Style" broke YouTube's view counter when it hit 2,147,483,648 views, forcing Google to upgrade their view counter to 64-bit. The music video’s views—2,344,870,718 at the time this article was written—surpasses the 32-bit limit.

8.  THE H2O MOLECULES IN A SINGLE DROP OF WATER // 1,390,000,000,000,000,000,000

A trillion has 12 zeroes. A sextillion has 21. This number is, surprisingly, more than a sextillion: 1.39 x 10^21 is the number of H2O molecules in a single droplet of water. The calculation involves another famous constant, Avogadro’s number: 6.022 x 10^23.

Based on the star count discussed above, there are twice as many H2O molecules in a single cubic inch of water—a few hundred drops—as there are stars in the entire universe.

9.  THE LUMINOSITY OF A SUPERNOVA // 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000

A supernova is the death of a star and an explosion bright enough to outshine galaxies. One of the brightest supernovas, discovered by astronomer Robert Quimby in 2007, shone with a luminosity of 100 billion of our suns.

Supernovae can give off 10^44 joules (or one foe) of energy in less than two minutes—the same amount of energy that our sun will emit over its 10-billion-year lifetime.

10.  THE NUMBER OF ATOMS IN THE UNIVERSE // 100,000,000,000,000,000,000,000,000,000,000,000,000,


With a span of 93 billion light years, the universe is vast, gigantic, and immense—you could even say hella big. Actually, you could literally say the universe is hella big, thanks to a petition started in 2010 by UC Davis student Austin Sendak to make "hella" an SI unit prefix for 10^27. The notorious Northern California slang joined the ranks of "centi-" and "kilo-" (not officially, but try converting hella units in Google or Wolfram Alpha). That makes the diameter of the universe 1.4 hellameters.

Our hella big universe contains an estimated 10^80 atoms. There is no prefix, made up or official, for that large of a number. It’s basically incomparable. Scientists believe all of that matter was created in the Big Bang. 

For more size comparisons from the massive to the minute, check out this interactive Scale of the Universe.