Even a 10-character long password consisting exclusively of numbers can be cracked pretty much instantly. To be really secure, you need not only a high number of characters but also a combination of numbers, upper and lowercase letters, and symbols.
For example, a 10 character long password consisting of all these factors could take five years to crack. When you increase the character length to sixteen, while keeping the other parameters the same, it would take one trillion years to hack your password.
However, there's an important caveat. As computing power increases, brute forcing attacks also get more powerful. As such, ten years from now, a new version of this chart will look very differently.
