user-1: Say I have created a paper wallet with one bitcoin address in a vault. What are chances that someone else will find the private key for this wallet?
Related: what are the chances of vanitygen address - private key pair collision?

user71141: There is a guy who has been testing this. He has ran a computer which generates addresses and checks the balances. Out of several years, processing millions of addresses per day, to my knowledge, he has found 3 with small balances. So, you can talk theoretical, where the chances are practically zero, but when there is someone who has attained at least 1, then perhaps it's not as unlikely as the math suggests.

user13092: There are around 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible bitcoin addresses according to BitcoinTalk.org. This makes it a very small possibility of finding another address that is being used. So the chance is around %0.

user85: Essentially zero. They would have to find a private key whose public key hash matched yours. The public key hash is 160 bits long. If they had a billion computers, each of which could try a billion keys a second, and they tried for a billion years, they'd have much, much less than a one in a billion chance of getting it.

-1: <p>Say I have created a paper wallet with one bitcoin address in a vault. What are chances that someone else will find the private key for this wallet?</p>

<p>Related: <a href="https://bitcoin.stackexchange.com/questions/7676/what-are-the-chances-of-vanitygen-address-private-key-pair-collision">what are the chances of vanitygen address - private key pair collision?</a></p>
 71141: <p>There is a guy who has been testing this. He has ran a computer which generates addresses and checks the balances. Out of several years, processing millions of addresses per day, to my knowledge, he has found 3 with small balances. So, you can talk theoretical, where the chances are practically zero, but when there is someone who has attained at least 1, then perhaps it's not as unlikely as the math suggests.</p>
 13092: <p>There are around 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible bitcoin addresses according to <a href="https://bitcointalk.org/index.php?topic=24268.msg304195#msg304195" rel="nofollow noreferrer">BitcoinTalk.org</a>. This makes it a very small possibility of finding another address that is being used. So the chance is around %0.</p>
 85: <p>Essentially zero. They would have to find a private key whose public key hash matched yours. The public key hash is 160 bits long. If they had a billion computers, each of which could try a billion keys a second, and they tried for a billion years, they'd have much, much less than a one in a billion chance of getting it.</p>
