I’ve heard it said that the odds of you being born is roughly one in 400 trillion, which is quite a long shot. As it turns out, your odds of existing are way worse than that.
Years ago, Ali Binazir wrote a long post (it’s gone, but archived version here) that walks through all of the odds.
He ultimately comes to the conclusion that the odds of any of us existing exactly as we came to be at roughly 1 in 102,685,000. That number is impossibly large to get our heads around. For comparison, the number of atoms in the known universe is roughly 1080. That number is also unbelievably large, yet pales in comparison to the odds of us existing.
His example to explain it:
So what’s the probability of your existing? It’s the probability of 2 million people getting together – about the population of San Diego – each to play a game of dice with trillion-sided dice. They each roll the dice, and they all come up the exact same number – say, 550,343,279,001.
I say all of this, because there is an excellent infographic that walks through all of his logic for that number. You can see it below, and click through for a full-size version.
The fact that you exist is literally a miracle.