How old do you need to be to get married according to the Bible?

The rule seems to be "If there's grass on the field, play ball."

Bible doesn't really have any guidance on that. And some stories seem to suggest that women were married as soon as they were teenagers.

1

Generally speaking, anyone who had reached puberty was considered marriageable up until relatively recent times.

1) when God tells you to

2) God will tell you and the spouse that a certain age is appropriate/inappropriate

3) it won't be prepubescent or perverted

4) follow God and God will let you know and lead you

Old enough for your father to sell you to the highest bidder.

If it bleeds it breeds, baby!