Horse Race Predictor

This horse race predictor runs your race 20,000 times. Put in the runners with their odds, or with your own ratings if you price races yourself, and it gives each horse a chance of winning, of finishing in the places, its fair odds and the forecasts and tricasts most likely to come up. It won’t name tomorrow’s winner. What it does is show you, in numbers, how often the favourite gets beaten and where the value is if your ratings disagree with the market.

How the racing predictor works

Every horse gets a strength. From odds, that’s its share of the book once the bookmaker’s margin is stripped out: in a race where the prices add up to 113%, a 2/1 shot’s 33.3% becomes about 29.4%. From ratings, every point of difference makes a horse a little stronger, and the “how predictable” setting decides how much a point is worth. A small conditions race where the top-rated usually wins is “very”; a 20-runner handicap is “wide open”.

Each simulated race then gives every runner a random dose of luck, ranks them, and records who won, who placed and in which order. It’s a standard model in racing maths (you’ll see it called Harville or Plackett-Luce), and it has a known flaw worth knowing: it slightly overrates favourites to finish second and third. Treat the place figures as a good guide rather than gospel.

Using your own ratings

This is where it earns its keep. Say you rate Saltmarsh 92 and the market has it at 4/1. Switch to “My own ratings”, type your figures, leave the odds in, and the table adds a value column: your chance times the price. Anything positive means the price is bigger than your ratings say it should be. If you build ratings from times, the CasinoCalcs speed figures calculator turns a race time, going and beaten lengths into a figure you can drop straight in.

Be honest about the limits. Your ratings miss things the market knows, like a stable whisper or a horse that hates the ground, and the market has a lot of money behind it. If your figures disagree with every price on the card, the likelier explanation is the ratings.

Forecasts and tricasts

The predictor also counts orders of finish, so you see the most likely 1-2 and the top five first-three combinations with their chances and fair odds. Compare those with the dividends or a bookmaker’s forecast price. The tricast and forecast calculator works out the cost and returns once you’ve chosen your combinations, and the ready reckoner lists returns at every price for a straight win or each way bet.

No model beats racing’s randomness every time. BeGambleAware.org is there if betting stops being fun.