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### How many lengths in a second in horse racing?

When constructing speed ratings for a race you need to know the finishing time for each horse. However, if you are only given the finishing time for the first horse to pass the finish line, which is often the case in UK horse racing, then you will need to know the distance by which each horse was beaten. From the 'lengths beaten' for each horse you can calculate a finishing time for each horse as a length is equal to a certain fraction of a second, as given below.

Always use the correct lengths per second for the race run. It used to be that 1 second always covered 5 lengths but since June 15th 2008 the British Horseracing Authority has set the following distances as equating to one second of time for all UK horse races. In some books (especially American ones) you might see 5 lengths per second as being the norm. If you do that with UK times then you will end up with inaccurate speed ratings.

Flat - Turf

6 lengths per second on going Good or quicker

5 lengths per second on going Soft, Good to Soft in Places, Soft or slower

5.5 lengths per second if the going is between the above (Good to Soft or in places etc.)

Flat - All-Weather Track

6 lengths per second at Kempton Park, Lingfield Park and Wolverhampton

5 lengths per second at Southwell

National Hunt - Over jumps

5 lengths per second on going Good or quicker

4 lengths per second on going Soft, Good to Soft in Places, Soft or slower

4.5 lengths per second if the going is between the above (Good to Soft or in places etc.)

Calculating finishing times for horses placed after the winner

Listed in the results you will see the lengths beaten for each horse plus some abbreviations as follows.

dh - dead heat, assume time is equal to the horse ahead
ns  - nose, .02 of a length
sh - short head, .05 of a length
hd - head, 0.1 of a length
nk - neck, .25 of a length

It is a simple matter of adding up the lengths beaten and dividing this figure by the lengths per second as determined above.

Example

A flat race, ridden on good to firm ground, is won in 60 seconds. The third placed horse finished 2.5 lengths behind the second placed horse, which finished 1 length behind the winner therefore the third placed horse completed the course in ((2.5 + 1) / 6) + 60 = 60.58 seconds.

Note that the further back in the finishing order a horse is the less accurate the finishing time for that horse will be. Beaten horses tend to canter home after the main placings have been decided and so the timings for these horses will be false.

To avoid false speed figures your speed rating system will need to either have a cut off at a certain number of places or lengths behind the winner. Two or more horses that fight out the placings can be thought of as racing at full-speed. Well-beaten horses cantering home outside of the placings can be disregarded. The horse can alternatively be classified as out-paced or out-classed until such time that it places in a future race and is ridden out to the end of the race to give a true speed figure.

I recommend that you read Nick Mordin's Mordin on Time, which contains a wealth of data on speed ratings derived from finishing distances. From the information on lengths per second above and this book you will be able to create your own speed rating for any horse.

Bioenergetics and Racehorse Ratings is an alternate approach to creating speed ratings. Using the measurement of human performance as a template the book attempts to do the same with horses. Measuring the speed of humans is considerably easier because they run on standard tracks. Horses are far harder to evaluate because they run at varying distances and on tracks of which no two are alike. This book shows how to develop a model for the performance of race horses and from there, speed ratings are generated.

Speed Ratings for Racehorses - my own ideas for creating speed ratings

1. thanks very informative

2. But the question is how they measure the lengths in a race? Who decides that the the distance between 'x' horse and the winner is 5 lengths and what formula is using. Here in Greece for example the photo finish is timing all the horses in a race. Then they transform the time to lengths (now the analogy is 1 length = 0,17sec). Is it tha same in UK? can anyone inform me?

1. My own impression is that the lengths are calculated using a similar photo-finish system to the one you see used in athletics.

2. This is the photo finish
this one calculates the lengths FROM the time and not the oposite! Is it the same at UK?

3. I believe that in UK racing the first horse's time is taken from the photo but all other finishers' times are not given, just the lengths behind the winner.

I think there have been a few races with sectional times but it is not something that BHA wants to roll out to all races nor giving times to individual horses.

Irish racing does use the same system that you have in Greece.