Short answer? It's Incredible.
Long answer? Lotsa biiig numbers.
— The Bottom Line
Bitcoin seed phrases provide an incredible amount of security. Incredible isn't even a strong enough word for it.
Let’s talk about the odds of somebody getting the exact same seed phrase as you, which is also the odds of somebody being able to guess your seed phrase.
Do you play the lottery? A Powerball ticket is only $2, and all you have to do to win is pick 5 numbers from 1 to 69, plus a Powerball number from 1 to 26. Sounds easy, right?
If you guess the first 5 numbers correctly, you win a million bucks. The odds of that happening are 1 in 11,238,513.
If you guess all 6 numbers correctly, you win the jackpot ($930 million dollars as I type this). The odds of doing that are 1 in 292,201,338.
Did you notice how adding just one more number made the odds drastically harder?
Now, let’s compare that to Bitcoin seed phrases. Remember: Powerball numbers go from 1 to 69. The Bitcoin word list has 2,048 words. And unlike the lottery, the words in a Bitcoin seed phrase need to be in the right order too.
Here are the odds of someone randomly guessing a seed phrase.
For a 12 word seed phrase, the odds are:
1 in 340,282,366,920,938,463,463,374,607,431,768,211,456.
For a 24-word seed phrase, the odds are:
1 in 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936
That number is so large, it’s practically incomprehensible.
To put it into perspective:
There are an estimated 7,500,000,000,000,000,000 grains of sand on Earth. That's 7.5 quintillion! Think about how small that number is, compared to the total number of possible seed phrases. Wow.
A typical grain of sand has around 10,000,000,000,000,000,000 atoms. 10 quintillion! Multiple that by the total number of grains of sand. It's still nowhere near the total number of seed phrase combinations.
There are roughly 133,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 atoms on Earth. That's 133 duodecillion. I didn't even know that word existed until I looked it up. It's *still* nowhere close to the number of possible seed phrase combinations.
The bottom line?
A Bitcoin seed phrase offers incredible security. Nobody can possibly guess it, and nobody is going to randomly generate the same seed phrase as you.