How long should it take me to run 5k in order to enter a marathon?

Question

How fast should I be able to run, if I wanted to be able to keep up?

Answer 1

Most marathons do not have qualifiying times to participate....the more elite races like Boston, however, have qualifying times, but those have to run a specific marathon time....5k times do not play any role in whether or not u can run a marathon

Answer 2

As the above two said, you don't have to qualify for most marathons.  There are a few you do.

A 5K, being only 3.1 miles is no judge for how well you do in a marathon, being 26.2 miles.  There is a tremendous level of difficulty, both mental and physical with a marathon.  A 5K can be run in 20-odd minutes.

Answer 3

As the other poster mentioned, a 5k time is not required for any marathon.  You can enter most marathons as a walker as they have cut-off times that are 7-8 hours.  If you are wanting to do more than walk in one (and you are using the 5k time to estimate what your time would be), you really need a longer race to more accurately predict a finishing time.  A 10k time is okay to use, but the best is a half-marathon.