How to calculate the win payoff from horse racing odds?  

Calculating the expected payoff on a win bet is easy once you get the hang of it. Example:

Odds in horse racing are expressed as fractions, such as 8-5 or 5-2.

The win payoff is almost always calculated off a $/£2 wager and can be obtained thus: multiply the first number in the fraction (the numerator) by 2, divide the sum by the second number (the denominator), and add 2 to cover your original bet. So in the case of the 5-2 horse, the math looks like this: 5×2=10/2=5+2=7.

In other words, a $/£2 bet will return $/£7.

The actual payout after the race is declared official may deviate slightly due to an accounting practice known as rounding, but it should be very close to your prediction.