# The RW Race-Time Predictor

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23/11/2004 at 13:39
Hello all

we'd love to know whether this calculator (click the link above) matches your real-life race times.

It's based on a well-established formula - what do you think?

My first reaction was that its predictions were too fast, but I think that was because
a) I have a bit more speed than endurance; and
b) my instinct was to try to predict times at the extreme ends of the distance spectrum (eg marathon time from 5K time)

Sean, RW
23/11/2004 at 13:52
Well, it thinks that I should be about a minute faster over 10k than I've ever run. That's probably about right though as I'm better trained for endurance and prefer racing longer distances.

I very much hope it's accurate, because it's tipping me for a 2:53 marathon ;o)
23/11/2004 at 13:56
Seems pretty accurate for me, but my 10k time is quite slow for my marathon time compared to a lot of other people's.
23/11/2004 at 14:24
It thinks I should be slower over 10K than I actually am. This is based on 10 mile and half times.

About a minute out from my PB of 36:58, based on a 10 mile time of 1:02:43.
23/11/2004 at 14:43
I think it works pretty well - my 10K PB predicts a half-marathon time less than a minute quicker than my actual best half. Frustratingly, the two half-marathon times are either side of my goal of 1:45! So, there's hope!

I have a copy of this formula in my running log to give me an idea of how easy or hard a run really was - every run is converted to a predicted time for a half-marathon so that I have a standard to measure against.
23/11/2004 at 14:44
My 10m time would predict a sub 2:40 marathon, though reality is different, 12 minutes behind. Based on shorter distances, I ran faster times than predicted.
23/11/2004 at 15:09
It's great news for me because my 10k PB of 42:28 predicts my marathon time as being 3:15:09 and as I'm going for sub 3.15 in 5 months time, it's an indication that providing I get the training is, I should achieve it without too much difficulty...
23/11/2004 at 15:27
Works within parameters give or take a couple of minutes on the marathon time
23/11/2004 at 15:27
I suppose that what it doesn't take into effect is that each race is different. So its an indication only. That's unless your running around a track.
23/11/2004 at 15:29
Also if you use it to predict 10K from a 400M time then its waaaaay off.
23/11/2004 at 15:45
yes, the formula was found to work best for 3.5 mins to 4hrs - (or 230 mins to be precise). I think it mentions that on the page
23/11/2004 at 15:47
23/11/2004 at 15:52
URR, I knew you were in 2:40 shape:)

Well according to my recent marathon I'm in 35:17 10k shape - let's see if we can take a couple of secs off that on Sunday;)

My 10k pb predicts a sub 2:35 marathon - lol!!
23/11/2004 at 15:58
Just input a recent run I did for 13.1 miles, not a race but just ran a bit faster than normal, RW predicts a 4.48.49 marathon time yet the mcmillan predicts 4.52.10, about 3 and half mins difference!! My marathon PB is actually 5.11.

Both times do fit in with my aim to do 11 min miling for my next marathon.
23/11/2004 at 16:01
the only time i could put in as an official time is a ten miler this predicts a 10k time of just over 52 mins i need to do a 10k to see if i could do it a bit quicker than that hopefully
23/11/2004 at 16:30
It's accurate to one second for 10K/half, but not really for marathon.

A 2:53 marathon from a 37:42 10K seems a bit aggressive.
23/11/2004 at 17:42
It's pretty accurate although it seems I've still got a bit more room for improvement over the longer distances going by my 5k time. It predicts a marathon of 3:12:16, something to work at then for FLM:o)
23/11/2004 at 17:55
Sean, check out my post on the 2:30 thread here

http://www.runnersworld.co.uk/forum/forummessages.asp?UTN=36728&URN=11&dt=4&srchdte=0&cp=23&v=6&sp=

which I did a few days ago. It shoes how to test the relationship between your times. For my 5k, 10k, 10M and HM times the relationship is Riegel's exactly but with 1.0508 instead of 1.06. The r-squared value of the relationship for my pbs is 1 which is the real proof in Riegel's hypothesis when applied to me.
23/11/2004 at 18:27
Nice stuff, Mike. Do you mind if I lift that into a 'find out more' page?

Have you seen this race-time ranking calculator on RW US? It's a hidden link that has now been replaced by 'under construction' message on the front of their site, so I'm not sure what's going on there.

That's another one to adapt for the UK
23/11/2004 at 19:20
Mine get steadily worse the longer I run. Maybe I haven't done a flat marathon or half yet to compare though.

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