Horse racing odds
In practice, they always sum to more — typically between 110 and 130 per cent for horse racing — and that excess is the overround. In a perfectly fair market with no margin, the sports betting non gamstop implied probabilities of all runners in a race would sum to exactly 100 per cent. Understanding those differences is where value lives. The bookmaker margin is built into every price, but how wide that margin is varies enormously between operators, between race types, and between the fixed-odds market and the betting exchange. Horse Racing Odds Comparison — More on this topic at horse racing bookmakers.
The margin a bookmaker builds into horse racing odds is not fixed. If you bet at a bookmaker with a consistently higher overround, you need a higher strike rate just to break even. The worst overrounds appear in ante-post markets, where the uncertainty justifies — in the bookmaker’s view — margins that can reach extraordinary levels. The overround also tells you something about the race itself. The overround is 5.9 per cent, meaning the bookmaker has built a theoretical edge of just under 6 per cent into the market. It is the bookmaker’s theoretical profit margin before a single bet is settled.
On feature races — the Champion Hurdle, the Gold Cup, the Grand National, Saturday afternoon handicaps at major tracks — the exchange market is deep enough that you can back at the displayed price without difficulty. Where a bookmaker might offer 5/1 on a horse with a 120 per cent book, the exchange might show 5.5 (or 9/2 in fractional terms) on the same runner with a total market overround of 103 per cent. When bookmakers extend place terms on big handicaps — paying five or six places instead of four — they compensate by widening the margin on the place element of each-way bets. At the lower end, you find small-field Flat races — Group 1 contests with five or six runners where the form is well established and bookmakers compete aggressively on the headline price of the favourite. The difference between 3/1 and 7/2 is not dramatic on a single bet, but across 200 bets over a season it represents dozens of units of profit or loss.
Checking the overround before you bet is not something most punters do, but it takes less than a minute with a calculator or an odds comparison site. Small-field races with well-fancied favourites tend to carry lower overrounds (closer to 110 per cent) because the market is more efficient and bookmakers compete harder on the headline price of the favourite. The difference between 5/1 and 6/1 on the same horse in the same race is a 20 per cent increase in profit — free money, essentially, for the 30 seconds it takes to check a second bookmaker.
Our top Pace number will be in either the 1st or 2nd position at the first call 72.5% of the time. Our top win percentage horse wins 32.9% of the time. Forget the days of tireless past performance analysis, PDF downloads, and digging for angles or professional picks. This website assumes no responsibility for the actions by and makes no representation or endorsement of any activities offered by any reviewed racebook or ADW.
Ante-post markets on the Cheltenham Gold Cup or Champion Hurdle typically run between 140 and 160 per cent, which is lower than the National but still significantly wider than raceday. The aggregate effect across 20 runners adds up to a much wider margin than in a six-runner race. Across UK and Irish horse racing, typical bookmaker overrounds range from about 110 to 130 per cent. Understanding the typical ranges gives you a framework for evaluating whether the price you are being offered is competitive or padded.
On horses that are supported in the market — money coming in, price shortening — BOG adds nothing, because the SP is lower than the price you took. Best Odds Guaranteed is one of the most powerful tools available to horse racing punters, and it is routinely undervalued. Using the exchange as a benchmark — even if you ultimately bet with a bookmaker — is one of the most effective habits a punter can develop. The practical approach for most punters is to use both. If you back at 6.0 (5/1) and pay 5 per cent commission on your winnings, your effective odds are 5.75 (approximately 19/4).
That difference — roughly 10 per cent on the individual price — is the cost of the bookmaker margin. One person backs a horse to win; another lays it (bets against it winning). The betting exchange — Betfair being the dominant platform — operates on a fundamentally different model to a traditional bookmaker. Among fixed-odds bookmakers, bet365, Paddy Power, and William Hill tend to be competitive on feature races, while some smaller operators run wider books, particularly on less prominent meetings.
