General Discussion Triathlon Talk » Can you estimate a half marathon time based on your 5 k? Rss Feed  
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2015-07-29 9:27 PM

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Subject: Can you estimate a half marathon time based on your 5 k?
Is it possible to do a raw estimate of how fast you will run a half marathon based on 5 k time? I'm asking bc I need to give proof of time for a couple of HM and I only have 5 k's to go from.


2015-07-29 9:34 PM
in reply to: TriCDA


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Subject: RE: Can you estimate a half marathon time based on your 5 k?
Google Macmillan Calculator - You most likely will run a bit slower than whatever time it spits out. . .but it's a good ballpark number. The less miles you do, the more conservative you should probably be with the number it spits out.

2015-07-29 9:36 PM
in reply to: TriCDA

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Subject: RE: Can you estimate a half marathon time based on your 5 k?

Yes, they are called race equivalency charts. You can find them, or various calculators online. It doesn't just figure out a pace and convert it to a certain distance, because you obviously will be able to run faster at shorter distances. It's set up to give you a realistic view of what you COULD run, given a certain known time. Try this one:

 

https://www.mcmillanrunning.com/

2015-07-29 9:44 PM
in reply to: TriCDA

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Subject: RE: Can you estimate a half marathon time based on your 5 k?

Yeah McMillians is good if you put in the work for the HM training and the 5k is recent enough.  Any way, my 5k was 21 sec faster than my 10K, which was 22 sec than my HM. 10k was 2 weeks after the HIM and I was focusing on HM training at the time then had recover runs only before the 10k.  The 5k was a different reality 2 years before but still in a high fitness realm (lots of tri training).

2015-07-29 10:15 PM
in reply to: TriCDA

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Subject: RE: Can you estimate a half marathon time based on your 5 k?
Awesome guys. Thanks for sharing that site.
2015-07-30 10:53 AM
in reply to: TriCDA

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Subject: RE: Can you estimate a half marathon time based on your 5 k?
Originally posted by TriCDA

Awesome guys. Thanks for sharing that site.


Just keep in mind that those calculators are optimistic and tend to predict towards the faster range of what you might run.


2015-07-30 11:21 AM
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Subject: RE: Can you estimate a half marathon time based on your 5 k?

Yep, the Mcmillan calcs are good, but generally  too aggressive the longer the race gets, and particularly for the marathon. 

 

It assumes you're training on the higher end of volume for each race distance. For 5k-10k, doesn't matter much, since volume isn't as much of a limiter, but once at HM, and for sure the full marathon, if you're not logging the weekly endurance miles, you'll fall way short of the Mcmillan estimate. 

 

If you're new to HMs, and running <35mpw, you should probably add +7mins to the Mcmillan HM estimate - it'll still be an fairly aggressive target. 

 

(I have a lot more experience with the Mcmillan marathon equivalents, since they're heavily referred to in marathon forums, and unless the course/conditions are significantly easier, it's not unreasonable for most newbies to the marathon distance to run Mcmillan + 20mins compared to their 5k estimate unless they'er running near 70mpw.



Edited by yazmaster 2015-07-30 11:23 AM
2015-07-30 11:49 AM
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Subject: RE: Can you estimate a half marathon time based on your 5 k?

Originally posted by TriCDA Is it possible to do a raw estimate of how fast you will run a half marathon based on 5 k time? I'm asking bc I need to give proof of time for a couple of HM and I only have 5 k's to go from.

 

I have used 5-6 difference equations for estimating my 1/2 marathon time from my 5K time.  The one that was the most accurate for me was Jeff Galloway's Magic Mile Formula.  LINK

Most of the pace calculators that I used put me 5-8 minutes faster for an estimated 1/2 marathon than Jeff Galloway's Formula.  After running a dozen good half marathons I have never got even close to the times from the other pace calculators.

 

You can just enter your estimated mile run time in the top box (next to the GO button) at the weblink and then check the 5K time (second set of boxes down).  Adjust your magic mile time up and down until it shows your actual 5K time.  Then you can go down a few more Boxes to the 1/2 marathon time and that is what your estimated time will be.  

 

I don't know how well this equation works for other people, but It spot on for me.



Edited by BlueBoy26 2015-07-30 11:59 AM
2015-07-30 1:53 PM
in reply to: yazmaster

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Subject: RE: Can you estimate a half marathon time based on your 5 k?
I think how accurate MacMillan is depends a lot on one's strengths and weaknesses as a runner, and the focus of one's training. I had the opposite observation looking at my PB's from my younger days--they tended to be overly optimistic for the shorter events, with the exception of 5K since I ran that event a lot (HS, college, road races, cross country, track) and probably knew how to burn all my matches over that distance, as well as the longer distances that seemed to come more naturally. Definitely if OP is not putting in the mileage and specific pace workouts for HM, and has little experience pacing it, the MacMillan time is likely to be overly ambitious, assuming the 5K time reflects his best effort and current fitness.
2015-07-30 3:13 PM
in reply to: Hot Runner

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Subject: RE: Can you estimate a half marathon time based on your 5 k?

Originally posted by Hot Runner ...Definitely if OP is not putting in the mileage and specific pace workouts for HM, and has little experience pacing it, the MacMillan time is likely to be overly ambitious, assuming the 5K time reflects his best effort and current fitness.

Yes the mileage and specific pace workouts for HM is an important point.  I don't think any of the replies over looked that it was just assumed that if you need an estimated finish time for a couple of half Marathons that you are training for half marathons (or what ever distance they are required for.  You know what they say about assumptions.  So...best to not assume anything and clarify up front.  Thanks for making that point.  :-)

Originally posted by TriCDA ...I need to give proof of time for a couple of HM and I only have 5 k's to go from.

What type of "Proof" do you need.  With a qualifying HM time you can skip the lottery and get a guaranteed spot into the New York Marathon.  For my AG the qualifying time is 1hr 23 minutes.  I did that in two out my last three half marathons.  For proof that you have qualified for an automatic spot you have to submit what race you ran your qualifier and then race organizers have to go to the official result for that race or the race director and verify your time.  If you need "proof" of a half marathon and you have never run a half marathon you are out of luck.  There aren't going to be any recorded times.  If the proof is to serve as a qaulification then you are going to have to do a half marathon to qualify and then prove that you did it.  If you just need an estimated finish time to be seeded in a large race that uses wave starts, then make your best guess.  My first HM was the Nashville Country Music Marathon which attracts over 30,000 runners.  They do about 30 waves starting every minute.  I didn't use any equations to estimate my time.  I just made a guess.  It turned out that I got to the race late and had to start about 8 groups further back than I was assigned.  Started 8 groups back was NOT a problem at all.  I made a bad guess as to how fast I was was too and finished 10 minutes ahead of what I had put down for my estimate.  That wasn't a problems either.  If 30,000 + people had tried to all start with the first group the streets would have been bottle necked.  As long as the the starts were spread out their was plenty of room for everyone to run they own race.  It didn't matter is slower people were at the front or faster people at the back because everyone had room to move around and go their own speed.

 

So....if you need "proof" of a 1/2 marathon time, the only way to get one is to run a sanctioned race that records official times.  If you just need an estimated time (i.e. to be assigned a starting group at a race) then about anything +/- 30 minutes will work.  :-)   

 

 

 

 

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