A better rider lifts a horse's chance by roughly the same proportion whatever it is running in — so what that is worth in cash is the extra win chance × the winner's prize. Both grow together across the card, which is why the same upgrade is worth almost nothing in a seller and a great deal in a valuable race. Pick a code below: everything on the page is then measured inside that code, not borrowed from the others.
Enter the total prize fund advertised for the race, not the winner's share — the winner's share is worked out below from the field size and the country, because the column that is supposed to hold it means different things in Britain and Ireland.
Off by default, because for most bookings it changes nothing. Published riding fees are a flat scale — you pay the fee to whoever rides — so the fee is not a cost of upgrading. The only incremental cost is the rider's percentage on the extra prize money, plus any retainer, and retainers are not in the published scale.
The published table, rebuilt on the corrected prize column and pooled across codes. Rows are bands of the jockey-blind model's win chance, which is not the same as the price-implied chance the calculator above uses — the blind model is deliberately less informed than the market, so a 33/1 shot sits several bands higher here than its price suggests. Read this as the shape of the result, and the calculator for a specific ride.