The first step in beginning a training program is figuring out what pace you should train at. 

Running fast all the time will not make you a fast runner.  Consequently running long and slow all the time will also not make you fast.  You must use a combination of fast and slow running in order to improve and lower race times.  When to run fast and when to run slow can be challenging to figure out for yourself.

After you have spent some time base building, which is basically slowly building up your weekly mileage to the average mileage you plan on running during your training program.  Meaning that if you currently only run 15 miles a week and you need to average 40 or more miles per week while training for a marathon, you slowly build up your base miles from 15 to about 35 or so. Once this has been accomplished and you are ready to begin your training program it’s a good idea to run a race to gage your current fitness level. 

If you plan on training for a 1/2 marathon or marathon then a 10K is a good distance to race to get a base race time.  Take your race time and plug it into Greg McMillans running website. We will use 45:11 for the purpose of this post.  You will find that by entering this time Greg estimates based on scientific calculations you could run around a 3:32 for a marathon.  What might surprise you is that this means your pace for a long run should be between 8:36 and 9:06.  You do not attempt to run your long runs at the average pace of 8:06 that you plan on running your marathon at.  Further it might surprise you that recovery runs should be at a pace of 9:36 – 10:06. 

When I first started training for marathons I would run my long runs around a 10 minute pace.  I believe this did me a huge disservice and ultimately caused me to have a slower time than I was capable of.  My long runs should have been between a 10:30 – 11:30 pace[work backwards by plugging in your marathon time to see if you trained in the optimal training zones].  You may be thinking to yourself that a 30 second difference in pace on a long run isn’t much of a difference, I’m here to tell you it is.  You do not get the long run training benefits if you are running the wrong pace on your long runs – be that too fast or too slow.

I have found based on my own personal training that McMillan’s calculations are usually pretty dead on.  There have been times I have not been able to run as fast as he stated and times I have been faster than he thought, but overall it has given me a baseline of what times I should train at and what I am capable of running in a race.  Simply having the calculation tell me a faster number than I thought possible has helped me push myself during races and lower my times. 

Bookmark this running calculator and use it as a tool in your fitness arsenal.  Re-evaluate your times throughout the season as your fitness improves.  If you run races throughout the training period, plug the time in and see if you are still on target for your goal marathon time.  Decide whether you need to adjust your goal faster or slower.  Also be sure to read Greg’s explanations of equivalent performance and optimal training paces.


  1. the mcmillan calculator is my best friend :)

  2. bookmarking the calculator, thanks

  3. RunningLaur says:

    I LOVE McMillan's calculator – I think I have the full spread, spot on, of times now, haha!

  4. Shellyrm ~ just a country runner says:

    Great info.

    I know I keep running too fast because I run what I am used to feeling and have a terrible time slowing down. But a new garmin may be under my tree this year which will help keep me on pace better.

    Merry Christmas

  5. Melissa Fair says:

    I'm completely new to running and training and would love to hear if anyone has tips for how to keep at it when you have little ones. I have an almost 3 year old little girl and a 7 month old little boy so sometimes getting to run just seems difficult or I just feel too exhausted to even try. Any and all tips would be great.

  6. What I love most about the McMillan calculator is how specific and detailed it is. It is interesting when I put in my 5k time versus my 5 mile time versus my half marathon time how much the results change for my estimated marathon finish time. Obviously the half marathon time is most accurate but it's fun to play around with.

    I find it VERY challenging to SLOW DOWN but I know it's important.

  7. Thank you for this link! I feel so much more intelligent about what I ought to be doing with my pacing. Awesome!!

  8. Carolina John says:

    That's very true! Great calculator.

    Have a great holiday Dorothy!

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