Race time predictor

How can I predict my race time?

You can predict your race time here from:

What training do I have to do?

The race time predictions are estimates of what a runner might achieve, if they train appropriately for the distance. It does not mean, for example, that if you train for a 5km and achieve a good time, then you will automatically achieve the corresponding time at the marathon distance. It shows what you could achieve at that distance, if you train properly, given what you have achieved at another distance.

How accurate are the predictions?

They seem to be pretty good predictors of performance. They are, however, based on average reduction of speed as the race distance increases, and this relationship will vary from person to person (as well as on the type of training they do: see above). There is therefore a significant margin of error around the estimates.

The margin of error is bigger if the gap between the distances is large. In other words, a half marathon will typically be a better predictor of marathon performance than a 1 mile race.

What is the age-grading prediction?

The age grading prediction assumes that that the runner will run the same age-graded performance at every distance. So, for example, if the runner has run a 10km at 62% of the world record speed for his or her age and sex, the calculation assumes that the runner would run 62% of the world record speed at each distance, and calculates what time that implies for each distance.

What is the VO2 max prediction?

The VO2 max prediction works by estimating your VO2 max, given the performance you have entered, using the Daniels and Gilbert VO2 max formula.

The formula is then used in reverse to estimate your likely speed at the other distances. (The times are found by solving the formula numerically for a given VO2 max.)

What is the Riegel formula prediction?

Peter Riegel’s formula is: t2 = t1 * (d2 / d1)^1.06

This formula was devised by Pete Riegel and published (in a slightly different form) in Runner’s World. Riegel later refined the formula for other sports. This formula has stood up well over time, and has the merit of simplicity. It says, roughly speaking, that a person’s speed declines by around 6% when the distance

What is the Cameron formula prediction?

Dave Cameron found that doing a regression comparing times and distance was futile; but that a model to predict speed produced a good formula which worked well for world records, US national records and collegiate records. He found that the model does well for post-1945 records at the 800m through the 10000m; and that from 1964 it also worked well for the marathon.

The Cameron model is

a = 13.49681 – 0.048865*olddist + 2.438936/(olddist**0.7905)

b = 13.49681 – 0.048865*newdist + 2.438936/(newdist**0.7905)

newtime = (oldtime/olddist) * (a/b) * newdist

Note that the distances are in miles; the times in seconds.

What is the Purdy formula prediction?

The Purdy point system is calculated from a table of running performances compiled in 1936 called the “Portuguese Scoring Tables.” These velocity measures were intended to be maximum possible velocity in a straight line. Each of these performances was arbitrarily given a Purdy score of 950. (World record times
in 1970 have about 1035 Purdy points.)

Purdy subsequently estimated an equation for the men’s world record performances (as of 1970). This enabled Purdy points to be estimated using the equation rather than the Portuguese tables.

The Purdy formula is often quite different from the other predictions; and I’ve now excluded it from these calculations.

See also

23 Responses to Race time predictor

  • Henry Bouwhuis:

    May 16 2008 I had a heart attack at the age of 53. I had and have been active all my life playing basketball with 20 year olds a month before I had the heart attack. In Feb 2009 I completed Cardiac Rehab and felt comfortable enough to start running. The goal was to run 10K in about 50mins. (???) I have now trained (most weeks) approx 3 years, 4-5 times a week running 5kms in approx 30mins and pushing weights and exercising afterward. Most workouts last about an hour. I haven’t been able to acquire the stamina to complete 10kms more than a couple of times always in over an hour. I can usually complete about 8.5km in about an hour. I have no joint issues although I have had countless sprained ankles and even broke the right one once furing my lifetime. I had two stents put in and another blockage that is approx 50% (no stent) at the time of the attack. Today I am off almost all of my medications, or have reduced the dosage to minimal levels. The Cardiologist can’t find any signs of cardic disease anymore and has even cleared me to play basketball again but I can’t find anyone my age to play with. My only complaint is at the end of a week I am very tired and wished I had better energy, usually a couple days off and then I start all over again. So I plan to continue running because I feel it is the best way to stay alive without being dependent on medications, I will be 57 next month and will continue down this path until I find something better.

    • Bob Rucker:


      I just stumbled on to your posting. I started running at age 47 after losing about 70 LBS and worked my way up to running various distance events all the way to marathons. At age 50, I experienced a heart attack with a full cardiac arrest. Luckily, their was a trained CPR responder and an AED nearby so I was lucky.

      As I went through rehab, I to experienced the fatigue you noted. I think it was mostly attributable to the beta blockers that were part of my medication protocal. My resting heart rate was right around 48 prior to the heart attack and the beta blockers dropped me down to just below 40. After 9 months of being on the more powerful beta blocker (metoprolol), my doctor switched me over to Bystolic. That helped a lot as my resting heart rate is back to the mid 40’s and when excercising, my heart rate is able to go up higher. The beta blockers really do a number on you.

      My cardiologist has encouraged me to continue running as he said my conditioning is the only thing (beside my emergency responders) that limited the damage to my heart. I ran my first half marathon only 58 days after my heart attack and ended the year running a full marathon 11 months after my attack.

      I’m guessing that a beta blocker is part of your medication portfolio and I had much improved energy levels after changing to a different type.

      Good luck as you continue you recovery.

      • Lee:

        So I had my yearly check up today and I asked the doc if I was able to run a long distance marathon,well normall marathon and he said no it’s not a good idea .When I asked why he said not to put he heart under to much stress .Now I have been running for about 3 years but only short distances and now joined a running group that are training for marathons ,what the hell do I do now .

        • Mike Lucas:

          Hi Lee,
          I would recommend to follow the advice of Dr. Phil Maffetone, get a heart-rate monitor and do all of your running at a easy-to-moderate pace (Zone 2 or MAF heart rate). Dr. Maffetone focuses on health first, making sure that your running does not adversely affect your health (heart or otherwise). By doing so your fitness will improve long-term. It worked for several athletes he coached including Mark Allen (multiple Ironman world champion).

          For more info see his book “The Big Book of Endurance Training & Racing”. For a sneak peek you can see: http://www.philmaffetone.com/files/9954/Want_Speed_Slow_Down_2007.pdf

          Good luck!

    • paula:

      Good luck to you and well done. So many people would have just plonked themselves on the couch.

  • Mike L:

    Dear Henry,
    It sounds like you are doing an amazing job of keeping yourself in good health. However given how tired you are at the end of each week you may be doing what is known as “chronic cardio”. What isn’t very well known about exercise is that exercise is actually NOT good for us — it is the body’s response to the exercise that is good for us. Exercise breaks us down, but the repair process we go through each time actually improves our fitness. Yet that system doesn’t work if we exercise beyond what we can recover from.

    Please see marksdailyapple.com for fitness and nutrition advice that is far superior to anything you would find in the mainstream. (this is where the term ‘chronic cardio’ comes from; Mark Sisson also has a wonderful book entitled The Primal Blueprint that you should check out)

    Mike in Winnipeg

  • Fred Anderson:

    Sorry, I am missing something about the predictor, particularly the Riegel component.
    I am working on the assumption that the Riegel formula is T2=T1X (D2/D1)X1.06
    I put in a 5 minute mile as a base to look at predicted performances. The two mile time predicted by the Riegel formula comes at 10:25. Shouldn’t the time predicted by the Riegel formula for two miles be 10:36 — twice the distance and time (10 minutes or 600 seconds for two miles) + 6% (36 seconds) which would come out to 10:36 rather than 10:25. Sorry if I am being dense.

    • Charles:

      The Riegel formula calculation is correct. You have misread the hat notation “^” for a multiplication sign “X”. The hat notation signifies “to the power of”. For example, 2 squared would be 2^2, while 2 cubed would be 2^3. As such, entering your example into the equation would give 300 X (600/300)^1.06 or 300 X 2^1.06.

      2^1.06 = 2.084932

      300 X 2.084932 = 625.4796

      or 6:25

      • chrisgg:

        Thanks for explaining that. It’s puzzled me for a good while. I’ve never seen the cap used for power…not while I was at school anyway! I thought it might mean “increased by” or similar. So the explanation in the original notes above is a bit misleading when it talks (admittedly “roughly”) about a 6% decline in speed when distance is doubled, which implies to me a 6% increase in time over and above doubling. In fact the increase in time is 4.2% from 10m:00s (600s) to 10m:25s(625s). If talking roughly, it should say about 4%. Speed over 1mile at 5 min/mile = 12.00mph. Speed over 2 miles at 10:25 min/2 miles = 5:12.5 min/mile = 5.208min/mile = 11.52 mph. So decline in speed is actually 0.48 mph/12mph = 4.00%, not 6%.

  • Charles:


    10:25 not 6:25

  • Rodney Mills:

    I have taken part in 2 Park Runs over 5km can you confirm the world record time for a 77 year old male.

  • Ziad:

    Hi Mike

    Here you go the link of the master ranking, you can play with the data, outdoor, indoor or Road races, as well you have all the category age this is for Canada…. Enjoy it


  • ELI:

    I have leisurely ran half marathons for over 4 years now and curious how much I could realistically improve my V02max/ race pace. About me: My avg half race pace is usually around 10-10:15min/m but I haven’t attempted to train properly/strategically over the past couples as I fell into the overuse bucket miserably with my first ever strict marathon training plan a few years back and it just kinda burned me to sticking to set plans for a while.Every year I also kinda die off of all running and only crosstrain/strength train May-Sept due to texas heat/run burnout but I have really worked this year to not have this null period after marathon season. It has seemed anytime my mileage gets around 30miles/wk I have ran into overuse issues even when I follow the <10%m/wk increase rule and regardless that I do plenty of crosstraining/strength work so over the years Ive come to only run about 12-15 miles/wk max plus crosstrain to "train" and achieve this race time. Im "calculating"my VO2max at 28 based on a recent workout and Im a 30yoF/ 5'7, 135lb, 20% BF.

    Anyhow I would LOVE to work for a fall/winter sub 2 hr Half- is this even a reasonable goal for a 20-40wk training period If I strategize my runs properly to peak race day? I have definitely learned training harder is not always training smarter so just wondering if this is attainable in this time frame… obviously I could kill myself attemptimg to knock out 800m repeats at a pace way faster than my fitness matches in attempts of achieving this goal but I know at this point that would hurt me more than help my running gains. Having trouble finding any reference on what typical goals/VO2max gains can be achieved over what time frame. THANKS!

  • bendrix:

    You learned the most important lesson there is in training – the importance of recovery. I think your half marathon target is definitely achievable and in that time frame too. Try this site – http://www.halhigdon.com/training/51139/home.html
    Myself and colleagues have used these programs successfully in the past so I wholeheartedly recommend them to you. As for 800m repeats, my own advice would be to do them at your target half marathon pace, not faster. It would be different if you were training for a 10k or 5k race perhaps. As for vo2 max, it is certainly a changeable that is to say – an improveable quantity. But it is not improved by speed training contrary to popular understanding, but by large volume purely aerobic work. Lots and lots of EASY runs that means, some of them LONG. See second last paragraph in section ‘Training and VO2 max’

    And the best of luck with your training 🙂

  • […] plugged my last 5K (22:18 at yesterday’s Race the Landing Recycle, Reuse, Renew 5K) into the Running for Fitness pace calculator, and those predicted times were around […]

  • Mike:

    Looking at you predictor page, what is an “SRC Handicap”? I did poke around trying to find the answer on my own, but to no avail.

  • The exponent in Riegel seems off. I find this fits the current world records well:

    WR_men = 3.72 * d^1.071 in minutes where d is in miles

    And I notice for myself, I slow more with distance and my PRs proportional to d^1.107.

  • VO2 max is a confusing to me. I’m a 56 year-old male, run 3-4 times a week, 5-8 miles a trip, and compete once in a while in 5Ks. I think my max heartrate is probably 180: my runs typically average 135-151, and I’ll run between 11:00 – 12:30 min miles. I do NOT follow a specific training regimen, just moderate to slow runs with occasional bursts of speed, usually near the end of the run.

    My PR in the 5K is 27:21 from 4 years ago. I just did a 5K is morning at 29:11, which I was pleased with. My problem is if I calculate my VO2 max, it’s 31.8, which is in the middle to lower part of fair for my age group. What gives? Am I in that smaller group of people that probably can’t increase my VO2 max very much (genetics) and shouldn’t give it much credo, or am I just dogging it and could step up my pace during the race?

    • chrisgg:

      You say you only compete once in a while. I think you might benefit from more regular competitive runs of anything from 5K, 5 mile, 10K, building up gradually perhaps to occasional 10 mile events and even the odd half marathon like I have done. They really sharpen your speed and increase motivation to train. The longer events also help all your shorter distances by improving stamina. Training runs of 5-8 miles, as you do, are perfect preparation for any race distance up to10 miles. I find the whole excitement of a race brings out my best performance. Only your best performances should be used to work out your VO2 Max. I wouldn’t too get hung up on VO2 values…they are basically only a measure of how fast you can go and you know that already. Long comfortable training runs are great for improving stamina and aerobic efficiency and your speed bursts during runs sound like a great idea….maybe a bit more speed work needed such as intervals over 200/400/800m. Personally, I don’t sprint intervals…just start slowly and build up to a steady 5K race speed. Intervals are a good way to warm up before any training or competitve run to get the circulation going and the breathing steady.

  • John:

    I’m curious if I should be concerned with heart rate(HR) levels when performing in races. I’ve been running regularly for 15 years and fit before then. Currently age 58, 5’7″ 148lbs. Weight about the save since a teen. I’ve been running every other day, 5-7 miles per. Racing events over the last few years have been under 8 min avg pace for 8Ks, 10Ks, 15Ks and two 1/2Ms while last 1/2M was 8:12 min avg. My resting HR is always under 50 and blood pressure numbers in good(low) range also. My normal training runs are usually at 8:15 to 8:40 avg pace.

    At my age and factors above, is an average HR of 160 (ranging 155-165) during races under a pace of 8 mins a concern or just normal for me?

    I use a TomTom sport with HR in the watch. I’d like to continue my PR improvements and eventual development into a few marathons for a wishlist – Boston qualification. (age 60+ group)

  • andreas buykx:

    My plan for this year is to run a marathon for the first time. I have started training for one before, and I have run several halves, and 15k, 10k and 5k races. When I enter my most recent times on these distances (approx 24min @5km, 51min @ 10km, 1:21@15km, 1:57@HM) the predicted marathon time goes from 3:46-3:54 to 4:03-4:08, roughly 12 minutes slower.

    What should I conclude from these predictions? I think the slower times are the more probable ones, I wouldn’t expect to finish faster than 4:15. How can I use the VO2 Max predictions given these fairly large differences?

  • Noah Clifford:

    I just wanted to note that I don’t believe this is too accurate, not for me at least. It’s saying I should be able to run a 9:42 2 mile based off of my 15:50 5k even though I’m running a 9:25 two mile, the one mile is off a bit as well. I’m not trying to bash this site, just suggesting they look into these inaccuracies. Sorry if I sound like a rude.

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