I was barely able to squeak in under 10:00 pace this morning with my 4 mile run which was intended to be a recovery run from yesterday’s 10 miler. None-the-less this has me questioning my expected time for the half. I found this website calculator that gives estimates for a different distance than the one you know for sure.
I plug in my 10k time (57:26, 9:15 pace) and can find that I should expect to run the half marathon in (2:06:26, 9:40 pace). But this course is flat and has a finish that is 137 feet lower elevation from the start. Since the 10k time was a trail run, how much better could I do? Hmmmm, 6 minutes 26 seconds, possibly, maybe, hopefully
I figure I don’t have enough time to go running all out the full 10k as a test but maybe once. But I can test a 5k a few times. So the stair step according to the calculator is this:
If I can run 3.1 miles at an 8:24 pace (25:12) then that means I can run 6.2 miles at an 8:45 pace (54:20). And if I can do that then I can then run a 13.1 mile half marathon at a 9:09 pace and that puts me on the finish line in just under 2 hours, by a second or two.
So any chance I get to go running on a flat 5k or 10k I will try and beat 25:12 or 54:20. If I can do this I should be able to break the two hour barrier in my first half marathon. If not then I will reset my sights on something like 2h 5m.
I found another calculator that only needs your mile time. It is not accurate for me, but there are a bunch of assumptions that may not hold true for me which might explain the discrepancy.