Running the numbers

I have an unhealthy relationship with McMillan’s Running Calculator. Some might call it obsession…

I recently posted about McMillan’s “equivalent performance” here.

I plugged in my latest marathon time of 4:26:02 to see what McMillan had to say.

Half Marathon prediction: 2:06:08
Actual Half Marathon: 1:52:29

10K Prediction: 56:41
Actual 10K: 47:59

5K Prediction: 27:19
Actual 5K: 22:36

So what does this mean? Do I just suck at marathons? (Kidding!) Do my strengths lie in shorter distances? Do I simply need more experience? Is it all mental?

Based on my 5K time, McMillan claims I could run a 3:40:19 marathon.

Based on my 10K time, McMillan claims I could run a 3:45:11 marathon.

Based on my half marathon time, McMillan claims I could run a 3:57:14 marathon.

With the right training and a good day, am I capable of achieving those times?

Am I over-analyzing?

Who knows. I am well aware the McMillan is only a guideline. But with the numbers being so far off, I definitely feel a bit stumped.

Maybe I should just stop thinking about the numbers for a while…


39 thoughts on “Running the numbers

  1. I clicked on the link when you had it this morning and I thought I saw something at the end saying that there are other variables including weather, the route and fan support. You had a muggy day. You had a race with mainly half marathoners in your way for 17K. Compared to other cities you had very few spectators to pump you up. And parts of the route are challenging due to out and backs and not great scenery.It might be different with different weather, a different course and more spectators, etc. I think the way you have to look at it is that your were 16 minutes faster in the second half alone. And you finished strong. That's huge.BTW the calculator kicks out similar results for me based on my marathon time (except I think my 30K time may have been slower than predicted with all the others faster).

  2. The caveats:"Finally, the predictor workouts are for a normal marathon – one with mostly flat terrain and good marathoning weather. Adjustments have to be made for difficult courses (like Boston), races where the weather can effect the race (hot/humid conditions or windy conditions) or races where you may not have support in either race competitors, the crowds or volunteers. In these cases, you would be wise to be more conservative and create a race plan that is appropriate for your particular race.In ClosingAll predictors are estimates. We just cannot control how you will feel on the day, what the weather will be like, how your competition will pan out and numerous other factors…"

  3. I've seen McMillian skew the same direction as it has for you several times in the past. When I was doing the same thing (but with my half time) last week, my 5k and half times basically matched, but I know that my current 5k PR is slower than I can actually run it. I think it's McMillian, not you 🙂

  4. McMillan is way off for me for the marathon as well. If I plug in any of my other PRs, it's within 30 seconds for every distance, except the marathon. Apparently I should be able to do it a lot faster than I did.Personally, I think the calculator is a bit too optimistic in calculating marathon times.MCM Mama

  5. My McMillan marathon prediction was way off too…this was based on 1 marathon, so I am not too sure, but I am pretty sure I cannot come close to what they predicted as my marathon pace. I am not sure how they calculate the pace(do they base it off elite runners' performances?)

  6. i was playing with mcmillan today and noticed that small changes in the 5K entry changed the HM number quite a bit. I don't know how accurately it can predict long distances based on short races and vice versa.

  7. My McMillan times are skewed like that too. I know for a fact that I am far better at the shorter distances–so maybe that's it? Problem is . . . I just keep wanting to run more marathons to see if I can catch up to my 5K PR on the McMillan Calculator! GRRR. I wish I had never found the damn thing! It drives me absolutely nuts-o! (Or maybe that's just taper madness . . . hmm).

  8. You're definitely not alone in this. I run way slower than what the calculator tells I should be able to in both the half and full marathon. It's dead-on for the 10K and close to my 5K. I figure, if running was that predictable, it wouldn't be as challenging as it is. 🙂

  9. I do the same thing with McMillan . . . so addicting! Must get some kickbacks from running shoe companies . . . keeps those fast "prediction" times out there as carrots to keep us running!

  10. I think MacMillan is more accurate the closer to the distance you want to run. There is such as huge margin between 5K and marathon I would think it would be hard to predict accurately. 30K to marathon is a better indicator I would think. Still, its nice to know the range or where you could be with training and all the stars aligning!

  11. I have the same obsession, except I use the Training Calculator on Runner's World's website. Maybe try that for comparison. If you've only run one marathon I'd say it's not a very good indicator of what you're capable of – the first one is all about finishing. Funny coincidence – my first marathon was a 4:26 too!

  12. My marathon and mcmillan times are way off. I try not too look at it too much b/c it just depresses me 😦 Though it is great for training purposes!

  13. This drives me insane too! I've plugged my times in every which way, but it seems the longer the race, the more inaccurate. I suppose you can just look on the bright side and celebrate when you've "beaten" what's been set for you. And I'm sure with enough training and a bit of luck, you'll "beat" that calculator marathon time too 🙂

  14. I noticed your skew towards the shorter races a long time ago. IMHO, McMillan is entirely right, if your speed was spread evenly across all the distances, you *should* be doing around a 4 hour marathon and BQing as one of your goals. Not being an expert on this, you probably have a higher percentage of fast twitch muscles, making you stronger in sprint-type events. If you enjoy marathons, then don't stop doing them, but understand that is perhaps not your forte.

  15. i have the reverse problem! my half time indicates i should be running a faster 5k and 10k…but, i think these calculators should be taken in stride. i wouldn't use a 5k time to predict my marathon 'cause those are two totally different beasts! a half/full comparison seems at least a bit more reliable to me.i would look at it as – you can totally chase down a sub-4, and work your way down from there 🙂 but, there's also nothing wrong with rockin' the shorter races and running marathons more for fun.

  16. I always thought those prediction calculators were way too optimistic, I wouldn't worry about not meeting the numbers. By the time you can run a 4 hour marathon, you'll probably be able to do a sub 1:40 half…

  17. Same here!! I have felt stumped. too. I do think the calculator is fairly accurate. So what's the deal? Simply put, I think it's race specific training. If we keep running with a deep base of miles, logging good MP runs, fueling and hydrating, hitting the perfect race day, we ought to get near the expected time?! Let's keep trying!

  18. I think the marathon is much harder to predict a time for than any other race because in order to accurately predict a finish time, the runner would have to maintain a consistent pace for SO long! It's one thing to run consistently timed miles in a 5K, 10K, even an HM, but for a full 26.2 miles? That's a toughie.However, that being said, I think you could run a sub-4 hour or better.

  19. Very rarely will your own times fall within the linear scale that McMillen predicts. It will more often fall in line for the elite marathoners, but not us regular joe schmoes. There is a great discussion about this. I'll see if I can find it and post it here for you.

  20. Yes, you're over analyzing. Stop it and enjoy your 16-minute PR. Continuing to go through these calculators takes away from the true story: you're a rock star. No calculator can tell you that.

  21. Ugh, McMillan. Yeah, my times are all over the place, too. My best 5K is right in line with my best 15K but that's it. Based on all of my shorter races, I should be able to run faster than the 4:12 I ran in the marathon. Maybe some day!!!

  22. Actually your number crunching gives me hope for a faster 5K. Sure my marathon will be slow, but I have a super speedy 5K ahead of me! LOL!Don't sweat the numbers. The calculator doesn't factor in hard work, dedication, and sheer determination.

  23. HA, I feel the same way about my shorter race times vs. my longer race times. But I gotta admit that I just don't really train for short races the same way I do for long ones, plus I don't seem to have the discipline to hold on to the pain of going hard & fast (long and slower is easier for me). But I think we can both make improvements to get closer to what those calculators say. Keep plugging!

  24. McMillan made me think I could BQ and still tells me I should be able to run a 3:35 Marathon… UGH!!I think it is a good guidline to help know what optimal paces you should use…but not living up to what McMillan says is NOT a fail in any way. It is a Tool and like any other tool parts can be a little broken..Hugs to numbers..I am a numbers freak and have inputted my NEW Pr's into McMillan every time..

  25. interesting!!!!!!!!!!!!!!! i have no idea what it means other than the predictions are just that… guidelines. but this could definitely get you all wrapped up in a headache if you spend too much time wondering, lol. i would just keep pushing yourself and see where it takes you! and run the distance you want to run!

  26. I think that your strength is in the short distances (half to 5k). not to say you couldn't get better at the marathon. I would say the calculators are just rough estimates and obviously you have shown you can do better than they predict based on a marathon time. I would say that a half marathon would best predict a marathon time because they are so close. Comparing a 5k and marathon just doesn't seem reasonable to me because they are totally different races – one is more about sprinting while the other is about endurance!

  27. truthfully i'd be crunching the numbers too, but it sounds like you've gotten some good info and advice, and know that it's a guideline only. Don't be hard on yourself k? You're a rockstar.

  28. Ha uhh WOW – I'm glad I've never messed with that calculator. I'd probably never stop….I would say *yes* – probably over analyzing just a little bit. Simply because you can hold a pace for a 5K doesn't necessarily translate that speed (through some Universal equation) to 26.2 miles!! In my opinion, the two just don't relate. You're using different muscles, different strategies, different training plans (obviously) and a different mentality altogether. It does look like a fun running toy though – adding to the list (garmin?! ehhh)…..

  29. i think SO much of the marathon distance is mental 🙂 obviously… but it also looks like you are speeeedy in the short distances too! just gotta keep doing them and it will come! i definitely think you have a speedy marathon in you though 🙂

  30. In talking to people about this it seems predicted times seem to be closer based on type of training and experience you have. My shorter to half times are very close, my marathon time is not. Marathons are all about endurance and experience. Most people I know that run them well have 3-5 years of high mileage base training to fall back on when the going gets tough after the 20 mile marker. Keep it up and I am sure you will see the gap in predicted times become smaller and smaller

  31. I have been playing around with McMillan a lot recently, too. I think for me (and probably you, too) I have underperformed to my potential in the marathon in the past. That's why your other distance predictions are so off based on the marathon time.For myself, I am taking this to mean I need to get tougher in tackling 26.2!

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