Predict my Debut Marathon Time

Marathons get real after 22 miles.

Your half time shows potential for 2:5x. But all will depend on how you react when the heavy lifting begins.

Between 2 and 4 hours. Tell me I'm wrong.

When I ran 2:47, my half was close to yours (1:20ish).

And I was averaging 70-75 mpw at the time.

I think you can dip below 2:50 fairly easily, should you put in more mileage.

Given the info you've provided my best guess advice would be to run 6:40 mile pace (2:54:45 pace) for 20 miles and either pick it up or hang on from there.

I wouldn't worry too much about your recent half marathon; if you're doing weekly 20+ milers, your legs are bound to be heavy. If you feel you should be in 1:21 shape and you taper well, I wouldn't be surprised if you coasted through halfway in 1:25 feeling breezy. I think it's best to err on the side of caution though, because you can lose a lot of time in the last 12k for going a little too fast for the first 30.

Good luck!

UK Runner wrote:

So I'm running my first marathon 3 weeks on Sunday. What do people think I can run based on the following info:

Ran a half last week in 1.25 (PB time is 79.59)

Averaged 53 miles per week for the last 15 weeks. 7 runs over 20 miles (a 23,22, 21 and four 20s).

My slow half last week is causing some concern. I knew I wasn't in PB shape but I figured I would be quicker than that. I've done recent sessions of a half distance training run in 1.26 which felt fairly ok. Plus a 10 mile tempo in under 65 minutes. So maybe it was a bad day at the office.

Anyway what do people think I should aim for?

Mileage is good, although not crazy high. Good long runs. Definitely could be a bad day at the office. I'd probably conservatively just say go for Sub 3. Better than trying to go out for a 2:55 and blowing up to run a 3:10.

OP - what did you end up running?