After all, it’s not some hypothetical matchup against all other men that you’re interested in, is it? If you’re honest with yourself, what you really care about is whether yours is the biggest dick your partner’s ever had. And that’s where the bad news begins.
Suppose your size is exactly average; that you’re in the 50th percentile for penis length. That means that 50% of men are smaller than you, and 50% are bigger. Does this mean you have a fifty-fifty chance of blowing your lover’s mind? Only if your partner had one man before you. If your partner had two men before you, the odds of their both being smaller are 0.5×0.5, or 25%. If three, the odds they were all smaller are 0.5×0.5×0.5, or 12.5%. In other words, there’s an 87.5% chance — 7 chances in 8 — they’ve seen bigger.
Let’s say you’re one of the lucky ones in the 75th percentile. Your dick is bigger than that of three out of every four men you see. There’s still a 58% chance that your partner (who’s had three men before you) has seen bigger!
In order to have an even chance of having the biggest dick that a partner with three previous lovers has ever seen, you have to be in the 80th percentile for penis size (about 6.25 inches according to the condom manufacturer LifeStyles). But that’s just an even chance. To have a good chance — say, 90% — you have to be in the 97th percentile (about 7.5 inches). And that’s if your partner has had only 3 men before you. It’s not too unusual to be the fifth or tenth or twentieth man, especially of a partner who’s very desirable.
None of these numbers mean anything if you can’t get it up when the time comes, so now that I’ve given you the bad news — don’t think about it.