In Great Britain approximately half of all races run are handicaps. A handicap is a race where horses are allotted weight based on their ability in order to equalize their chances of winning. If the handicapper has correctly assessed each horse in a race and they all run to their ability then in theory they should all cross the winning line at the same time.
The handicapping system is the responsibility of the British Horse racing Authority (BHA) and once a horse has run often enough to be assessed it is given an official rating by the handicapper. This rating will be in the scale of 0-140 for flat racing and 0-175 for jumps racing. A horse needs to have run three times or to have won on its' first or second run before it will receive a handicap mark. Once a horse has received a handicap mark it is eligible to run in handicaps. The horse's rating will determine which class of handicap it can enter.
Each point on the rating scale is equivalent to a pound in weight, that is, a horse rated 75 would carry 5lb more than a horse rated 70. The handicapper generally uses the weight of 1lb to equate to 1 length. The weight is carried in the form of lead weights added to the horse's saddle cloth.
The official rating is revised every week, going up or down or staying the same depending on how the horse has performed. The handicapper will often use other horses in the race as a yardstick by which to base the performance of a particular horse.
Should a horse win off a particular rating and there is time to run again before his official rating is revised connections may be tempted to run the horse again if a suitable race can be found. A horse in such circumstances is said to be "ahead of the handicapper". In some cases a penalty, an additional weight to be carried if the horse has won a race since the last revision, will apply to take account of improvement not yet reflected in the official ratings. If this is the case it will be explained in the conditions of the race the horse has won which are detailed on the racecard. Sprinters have a better chance of staying ahead of the handicapper because they can run more often than other horses.
When entries are received for a race the top rated horse entered is assigned the appropriate top weight, horse number 1 on the racecard, and the weights of all the other entries are calculated in relation to that horse.
When weights are allocated to horses entered into a race, any horse that is set to be given a weight below the minimum weight advised in the race conditions is know as being "out of the handicap" and is set to carry more weight than its rating would have suggested. This can occur because horses are allocated weight prior to the declaration stage at which point a number of higher weighted horses might come out of the race. The horse left with the highest weight is likely to be carrying less than the conditions of the race stipulated. The top rated horse's weight is then increased to match what the minimum top weight can be and all the horses below the top weight also see their weight increased accordingly.
There are other professional ratings services, most notably the Racing Post Rating, but these are not the horses' official rating. Only a rating awarded by the BHA is qualified as the horses' official handicap mark and is used by the trainer and owner when making entries for the horse.
Horses of different handicap ratings are eligible to run in certain types of races, restricted by the handicap rating they have.
Flat racing has seven classes with class 1 being the highest grade and class 7 the lowest. The classes are broken down as follows,
Class 1 Listed Handicaps 96-110+
Class 2 Heritage Handicaps, Handicaps of 86-100, 91-105 and 96-110 and Classified Stakes 0-95
Class 3 Handicaps 76-90 and 81-95 and Classified Stakes 0-85 and 0-90
Class 4 Handicaps 66-80 and 71-85
Class 5 Handicaps 56-70 and 61-75
Class 6 Handicaps 46-60 and 51-65
Class 7 Classified Stakes 0-45
There are also Nursery races which are handicaps for 2 years olds and Maiden handicaps which are for horses aged 3 or over who have never won, have run at least four times and who have a maximum rating of 70.
Jumps racing has six classes with class 1 being the highest and class 6 being the lowest. These are broken down as follows,
Class 1 Pattern (Group 1,2 and 3) and Listed races
Class 2 Open Handicaps and Handicaps 0-140+
Class 3 Handicaps 0-120 and 0-135 and Novice Handicaps 0-120 and 0-135
Class 4 Handicaps 0-100 and 0-115 and Novice Handicaps 0-100 and 0-115
Class 5 Handicaps 0-85 and 0-95 and Novice Handicaps 0-85 and 0-95
Class 6 National Hunt Flat Races and Hunter's Steeplechases
Note: A Novice Handicap is open to horses who before the beginning of the season have not won a race. A Hunter's steeple chase is a weight for age race restricted to horses that have been hunting that season and is only for amateur riders.
Apprentice jockeys, that is those just starting out in the profession, are allowed to claim an allowance when they are riding. What this means is that they are allowed to take off some of the weight a horse is due to be carrying. The theory being this is that the reduction in weight compensates for the young jockey's lesser experience. This is known as a jockey's claim and is shown in brackets after their name on the racecard. As the jockey gains more experience and rides more winners his allowance is reduced until they have ridden enough winners and are no longer able to claim any allowance. Once this happens they are said to have "ridden our their claim",
On the flat these jockeys are known as apprentices or claimers. They receive 7lb until they ride 20 winners at which point it is reduced to 5lb. Once they have ridden 50 winners they lose their claim.
Over the jumps these jockeys are known as conditionals. They received 7lb until they ride 20 winners, 5lb for between 20 and 40 winners, 3lb for between 40 and 75 winners and 1lb for between 75 and 95 winners.
Weight allowances can be claimed in all race types except Group and Listed races.