Predict Your Marathon Time



As the race approaches, marathoners want to know which pace is the right pace – the one that achieves the fastest time possible and avoids the all too common fade in the final few miles. This article discusses the three workouts that I use to gauge the best race pace for the marathoners I coach. The predictions are not fool-proof, but I find them to work for the vast majority of marathoners. As you prepare for your next marathon, these workouts can be helpful in your race planning.


The Fast Finish Long Run has quickly become a mainstay for competitive marathoners. I learned it from Gabriele Rosa – the coach of world record holder Paul Tergat – but many other coaches and athletes have used it successfully for years.

In the fast finish long run, you run the first eight to 12 miles of a 14- to 18-mile long run at your normal long run pace. However, over the last three to 10 miles of the run, you run faster and faster. Once you’ve become accustomed to this workout, I’ve found that if you can finish these very strong and fast, you are on target to achieve your marathon goal. Read this post to learn more about how to run a fast finish long run.

Fast finish long runs are very tough workouts so you shouldn’t do them very often or run too many of them in any one marathon training cycle.

I suggest alternating a weekly fast finish long run with a more typical weekly long, steady run. If you can run three to five of these fast long runs in the eight to 12 weeks prior to your marathon, they become a very accurate predictor of your ability to not just run the marathon but to race your best marathon.

Lastly, you shouldn’t ‘taper’ for your fast finish long runs. Instead, go into each one as you would any other long run otherwise the pace you achieve isn’t as accurate of a predictor of your best marathon pace.


A second favorite marathon predictor workout is a long distance race. I really like for my marathoners to race a half-marathon a few weeks prior to the marathon (though any race from 15K to 30K works). To get your marathon pace prediction, use my McMillan Calculator. Just select the distance of the race you ran and input your time. Hit submit and check to see your predicted marathon time.

Another estimate of your marathon time is to double your half-marathon time and add five minutes. For example, if you run 1:30:00 for a half-marathon then this method would predict that you could run 3:05:00 for a marathon. I find, however, that doubling your half-marathon and adding seven minutes is slightly more accurate for most runners. Doubling the half and adding five minutes seems to work really well for pure marathoners, those runners who do poorly in short races but excel (and love) long workouts and races. Alternately, Tim Noakes, author of Lore of Running, suggests that you multiply your half-marathon time (in minutes) by 2.11 to get your marathon time (in minutes). No matter how you do it, though, a long distance race is another great workout that can help you accurately predict your fastest marathon pace.

One note about how close to the marathon you should run a long distance race: I recommend a minimum of three weeks between a half-marathon and the marathon, though I prefer four to five. Also, the longer the race, the further away from the marathon it should occur.


The third prediction workout comes from the folks at Runner’s World and is called Yasso 800s. The theory behind Yasso 800s is that your time in minutes and seconds for a workout of 10 times 800 meters (two laps of the track) with equal recovery time (jogging slowly) is the same as the hours and minutes of your marathon time. For example, if you can run 10 times 800 meters in three minutes and 20 seconds with three minutes and 20 seconds recovery jog, then this predicts that you can run three hours and 20 minutes for your marathon. Run 2:40 for the 800s and you can run 2:40 for the marathon.

This is a hard workout so get mentally ready for it. The workout should feel like a 10K feels. Early repeats are fast but controlled like the first two miles of a 10K race feel. The middle repeats get harder and require more concentration and effort like the middle two miles of a 10k race. The last few reps are very hard like the last two miles of a 10K race.

My experience is that a Yasso 800 workout predicts differently depending on your runner type. Using the example above, my experience has been that 10 times 800 meters in 3:20 with 3:20 recovery yields the 3:20-3:22 for Endurance Monster-type runners. For Combo runners, the 3:20 Yassos predict closer to a 3:22-3:24 marathon (2-4 minutes slower than the prediction). And for Speedster, the prediction is 3-5+ minutes slower (for our example that would be 3:23-3:28) than the prediction.

Because this workout is easy to do, I try to include it two or three times in a marathon training cycle. It not only provides a good predictor of marathon pace but allows you to chart your increasing fitness – a big confidence builder.

I typically use all three of these predictor workouts with each marathoner I coach and recommend that you do the same. These three workouts give you a great overview of your total capabilities – your endurance and durability (fast finish long run), your ability to run fast for a long period of time (long distance race) and your aerobic capacity (Yasso 800s). Taken together, I find them to be very, very accurate.


All of these predictor workouts assume that you have done all the prerequisite training for a marathon – consistent volume of running, long runs, lactate threshold workouts, etc. You can’t just go run one of the predictor workouts and expect it to be accurate if you’ve not done the training. Without the proper prerequisite marathon training, you may find yourself in a world of trouble late in the race!

Also, aside from the long distance race, don’t taper for the fast finish long run or Yasso 800s workouts. Just do them as a normal key workout and get the result. I know that you’ll want to have a great workout, but in the end it’s more important to get an accurate picture of your marathon potential than to soothe your ego with a great workout that you tapered for.

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.


All 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. However, I’ve found that the predictor workouts described above offer marathoners with helpful information that can aid in race planning. Prepare the best you can, have faith in yourself, respect the distance, use these predictor workouts to establish a smart race plan and hope for the best on race day. Good luck!

Check out Greg McMillan’s Surviving the Marathon Freak Out: A Guide to Running Your Best Marathon


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Written By Greg McMillan
Called “one of the best and smartest distance running coaches in America” by Runner’s World’s Amby Burfoot, Greg McMillan is renowned for his ability to combine the science of endurance performance with the art of real-world coaching. While getting his graduate degree in Exercise Science he created the ever-popular McMillan Running Calculator – called “The Best Running Calculator” by Outside Magazine. A National Champion runner himself, Greg coaches runners from beginners to Boston Qualifiers (15,000+ and counting!) to Olympians.

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