Betting Odds Converter

Divide 1 by the decimal odds. Odds of 4.0 imply a 25% chance, and that figure is the win rate you must beat to break even.

Profit relative to stake. Odds of 5/1 return five in profit plus your stake, which is decimal 6.0. Odds of 1/5 return one profit for five staked, which is decimal 1.2.

A positive number is the profit on a 100 stake; a negative number is the stake needed to win 100. +200 is decimal 3.0 and −150 is decimal 1.667.

The amount by which implied probabilities across a market exceed 100%. A two-way market at 1.91 each side sums to 104.7%, so the bookmaker takes 4.5% regardless of the result.

To balance the book against money taken, and to reflect new information. A bookmaker aims to profit from the margin rather than from predicting outcomes, which is why heavy backing shortens a price.

When your estimate of the true probability exceeds the implied probability. It is the only circumstance in which a bet has positive expected value, and it requires your estimate to be genuinely better than the market's.

By setting odds so the implied probabilities sum above 100% and balancing the book so the margin is collected regardless of the result. They aim to profit from the spread rather than from predicting outcomes.

An exchange matches bettors against each other and charges commission on winnings; a bookmaker takes the other side itself and builds a margin into the odds. Exchange prices are typically closer to fair.

Whether the odds you took were better than the final odds before the event. It is the most reliable indicator of whether a bettor is genuinely beating the market rather than getting lucky.

Because decimal, fractional and moneyline are regional conventions describing the same thing. Fractional is traditional in Britain and Ireland, moneyline in North America and decimal almost everywhere else.

Two bets: one on a win and one on a place, at a fraction of the odds. It costs double the stake and it is worth understanding the place terms, which vary by field size.

Staking systems like doubling after a loss cannot change the expected value of a negative-expectation bet — they redistribute variance rather than removing the edge. The house margin is unaffected by how you stake.