How long off after a marathon?

It's all individual, some take a long time others don't take any. I took 7 days off after my first and 5 days off after my second. Had some tendinitis 3-4 weeks after starting up following the first one but have stayed healthy after the second, so it probably wasn't the lack of time off. If you're itching to go, there's nothing wrong with doing some easy running and starting to build back up.

Take at least 3-4 days off, at most 6-7. Then, jog easy for a week, do some very light speed work the next week and you should be back to normal by the forth week.

I've run 26 marathons and I usually start running again on the Wednesday after a Sunday race. I don't push the pace or run very far but just to work the kinks out.

Some people run the day after their marathon. After my first few I would take 2 or 3 weeks off, now I may take 2 or 3 days. Just keep the first few days back SLOW and EASY and let your body dictate how much you can handle.

See the quote of the day for your answer.

Personally, I got my first-ever overuse injury this summer (29yo, running for 16 years), after coming back too fast from a marathon. (I told myself that I was slowed by race-day heat/didn't feel that banged up, both of which were at least subjectively true.) I took one week completely off, but then got antsy, and was up to 30mi by the second week post-race. This was too much for me; I got patellar tendonitis; there went about half the summer. So be careful... probably better to err on the side of too much rest here than not enough.