Horse racing odds

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. Odds expressed in decimals are meant to show the total payout the punter receives, which includes the winnings and the stake. In today’s day and age where automobiles have substituted the four legged animal, horses still retain importance. Dave Massey previews Saturday’s action at Aintree, selecting his best bets for the races at 1.15, 1.45, 2.25 and 3.00.

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. 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 implied probabilities of all runners in a race would sum to exactly 100 per cent. Understanding those differences is where value lives.

When should you use the exchange, and when should you use a bookmaker? There is a subtlety that experienced exchange users understand and newcomers often miss. Flutter Entertainment, which owns Betfair, reported global revenue of $14 billion in 2024 across 13.9 million average monthly users, but the exchange is only one part of that portfolio, and liquidity varies enormously by market. Hundreds of thousands of pounds are matched, and the spread between the back and lay prices is narrow.

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That means BOG triggers on a meaningful proportion of bets, and the average uplift when it does trigger is typically between half a point and two full points of odds. Research on UK racing suggests that around 35 to 40 per cent of runners drift to a higher SP than their morning price. The value of BOG depends on how much Starting Prices drift from the early prices. That decline puts pressure on bookmakers to attract and retain bettors. It is a one-way ratchet in the punter’s favour — a free option on upward price movement with no downside risk. Check the exchange price on your selection before placing with a bookmaker.

Around major meetings — Cheltenham, the Grand National, Royal Ascot — bookmakers offer boosted prices on selected runners. If the exchange offers 6.0 and the bookmaker offers 5/1, the bookmaker is competitive after commission. Instead of setting odds and accepting bets against them, the exchange matches punters on opposite sides of a bet. At the upper end, you find big-field handicaps with 20 or more runners, where each horse price can be inflated by a few ticks without any individual punter noticing the difference. The individual difference may be small — perhaps 5/1 versus 11/2 — but across hundreds of bets over a year, that cumulative margin is the difference between a profitable punter and a losing one. The take varies from state to state and the money is used to pay taxes, purse money for the horsemen, expenses at the track, and the track’s profit.

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.

The exchange takes a commission on the net winnings of the winning side, typically between 2 and 5 per cent depending on the user’s activity level. The overround on the Grand National ante-post market can reach as high as 180 per cent — a level that would be considered predatory in any raceday market. It varies by operator, by race type, and by the time of day. If Bookmaker A is running a 115 per cent book on a race and Bookmaker B is running a 125 per cent book, Bookmaker A is systematically offering better value across the entire field. The 120 per cent book means the prices across the entire field are compressed, which means every price is slightly lower than it should be in a fair market.

Second, the exchange price reflects pure market opinion without any built-in margin, which makes it a more accurate indicator of the horse’s implied probability. First, it gives you a benchmark for whether the bookmaker prices are competitive. For any given horse, you can see the best available price highlighted, and the difference between the best and worst price is often two or three points of odds — the difference between 7/1 and 5/1 on the same horse in the same race. It does not require you to do anything special — just take an early price on a race where BOG is offered. Unlike free bets, which come with qualifying conditions and wagering requirements, BOG applies to every qualifying bet you place. A few bookmakers restrict BOG to races shown on ITV or feature meetings, excluding the smaller afternoon cards where drifts are more common.