That's a good question, I mean its not like you can take a measuring cup and see. However...Just a litle pre-cum is enough to get someone pregnant. Ask your local doc...Get back to us when you get the answer. We'd like to know too...Later

Pre-cum does not always contain sperm. In fact, it rarely does. But never over-rule it because these things do happen.

I did not know that thanks for the info kgirl16

Precum is actually pre-ejaculation fluid. So, now you know what it is, now, more important part – what does it contain?? Well, it contains really many ingredients among which can be sperm. Actually, it is more individual but in many cases sperm is contained in precum. Also, even if there is no sperm in it, if you recently had sex (or masturbating) and did not urinate in meantime, there is good chance that there is some sperm “leftovers” in your penis which will come out together with precum. Precum can “occur” at almost any time but it is usually not long before you really cum. It also can occur in cases when you “hold back” your ejaculation. In those cases you hold ejaculation but not the precum. I suggest you to test yourself while masturbating – “time” of precum is in most cases individual so you should check when it happens in your case.
Anyway, to conclude, if you don’t want to play with your life (as you put it) I would strongly suggest using condom every time you “enter”…