Track/XC: Determine Race Paces With the Horwill Rule

Dick Moss, Editor

You have a 400m runner who would like to move up to the 800m. What is his potential at the longer distance? Or your 1500m champ wants to try the 800. How fast should she run her race-pace workouts? Perhaps you use a multi-pace training system, in which your 800m runners, for example, train at 400m, 1500m and 3k paces. How do you determine the lap times for these other events?

The Horwill Rule will help you to ballpark these times. Developed by the late Frank Horwill, world class coach and the founder member of the British Milers' Club, the rule gives you some simple guidelines for estimating potential race-paces when moving up or down in distance.

The Horwill Rule
The rule provides simple calculations for estimating race pace. It varies slightly for males versus females.

For males, when moving up in distance between the major competitive events (400m, 800m, 1500m, 3000m, 5000, 10,000m) add 4 seconds per 400m (1 lap on a track) to estimate potential race pace.

For example, to determine race pace for a 60-second 400m runner wanting to move up to the 800, add 4 seconds to get 64 second/400m and multiply by two. His potential 800m time is 2:08, and 64 seconds/400m would be a good pace at which to train during race-pace workouts.

We can work all the way up to 15,000m (which is anaerobic/lactate threshold pace) using this formula:

  • 400m time =     60 sec
  • 800m =     2:08 (64/400)
  • 1500m =     4:15 (68/400)
  • 3000m =     9:00 (72/400)
  • 5000m =     15:50 (76/400)
  • 10k =     33:20 (80/400)
  • 15k =    52:30 (84/400)

This simple formula also works when athletes want to move down in distance (simply subtract 4 seconds/400m).

For females, simply add five seconds per 400m instead of four.

The Horwill rule will also indicate deficiencies in your athletes' training. For example, according to the rule, a female 800m runner with a best 400m of 65 seconds should be able to run a 2:20/800m. If she can only run 2:30, it's an indicator that she needs more endurance work and/or over-distance races.

Of course, the Horwill Rule provides a general estimate only. Its accuracy varies with the level of training and speed versus endurance abilities of your runners. And, as you get farther in event distance from your base event, the estimate becomes less accurate (i.e. a 400-to-800 conversion will be more accurate than estimating 10k time based on the 400m).

However, the rule is simple to use, and it gives coaches a general baseline to work with in estimating training paces.

Frank Horwill
Frank Horwill passed away on January 1, 2012. You can see more information about this legendary coach at:

1. Editor, “The 4-second rule—Frank Horwill.” Athletics, December 1991.
2. British Milers' Club,
3. Frank Horwill's 5-Tier System, Oct, 2012.

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© 2012, Physical Education,

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