What is the weight-for-age scale?

Horses start their racing careers as two-year-olds and three-year-olds, but, depending on code under which they compete, are not considered fully mature until they are four or five years old. Fairly obviously, without any weight allowance, younger, physically immature horses would be at a significant disadvantage when racing against their elders. It was to help offset this disadvantage that the weight-for-age (WFA) scale was conceived and introduced by Admiral Henry John Rous, who was appointed official handicapper at the Jockey Club in 1855. His approach proved successful in its aim of allowing horses of different ages to compete against each other fairly and has remained, virtually unchanged, ever since.

The WFA scale is a graduated, or sliding, scale, which dictates the weight allowance received by younger horses from older ones as they progress, month-by-month, through the racing season. The weight allowance varies according not only to the age of the horse concerned and the time of year, but also, because increased stamina is a function of overall aerobic capacity, muscular endurance and, hence, maturity, the distance of the race being contested. A three-year-old racing over 5 furlongs at the start of October, for example, would receive no weight allowance from its elders, but 1lb over 6 furlongs, 2lb over 7 furlongs and so on, up to 11lb over 20 furlongs, or two and a half miles. Different WFA scales exist for Flat and National Hunt racing, and for horses bred in the Northern and Southern Hemispheres.