(spoiler) how old do you think roland is at the end of the seventh book and...

[bluesology]

It's a rough way of figuring it - but Roland passes over 200 levels of the Tower at the end. That's not an exact number since they say that sometimes multiple floors represented the same years but none the less, pretty old would be my impression.

[bgheff]

A quick note. Just because it's been hundreds of years since anyone has seen a gunslinger out at the ends of mid world does not means Roland is hundreds of years old. We don't know how long before Gilead fell that troubles were brewing. It is likely Gunslingers were recalled from far off areas to deal with issues closer to home as the situation grew.

[Can-'Ka No Rey]

According to the Concordance, when Roland wakes up in the Western Sea, is 36 years old (336 in "Mid-World time") but his body has aged 10 years. So he feel (and probably looks) 10 years older.
The events in DT2 'till DT7, has passed about 6-7 years. 'Cause Eddie arrives in Mid-World at the age of 21 (if I'm not mistaken) and in the DT7 he has 27.
So, to me, Roland in The Dark Tower VIII is about 42-43 years old, but his body is 10 years older, that's mean 52-53 years old.