How old is Peter Parker (earth 616)?

?????

every 4 years in real life is a year in marvel. Peter was in his late teens when he began so I think he's in his late 20's now.I think 29?

I'd put him at 27. Marvel doesn't want him too old.

Somewhere around 25-30.

28

how can we decide, marvel's ways are hard to understand

He's about 30. If he was 16 when he became Spider-Man (which I believe he was), then he would have been 29 when Thing celebrated his barmitzvah comemmorating 13 years as the Thing. That was a few years ago, so that puts him in the neighborhood of 30.

Mid to late twenties i'd guess.

Mid-late twenties, I guess.

As old as the next Spider-Man writer wants him to be. He should be in his early twenties if anything.