Bet Builder Calculator

The tool starts with your estimated probability for each selection and multiplies them together. It then applies the Combination Factors you enter to account for correlation between the selections.

For example, if two selections have estimated probabilities of 70% and 60%, their combined probability would be 42% if they were independent. A Combination Factor can then adjust this probability to reflect the relationship between the selections.

This allows you to compare the fair price for your Bet Builder with the odds offered by a bookmaker.

Yes. The calculator is designed to use your own estimated probabilities for each selection.

This allows you to calculate fair Bet Builder odds based on your own assessment rather than relying on the bookmaker's implied probabilities.

The resulting combined probability, fair odds, Edge and Kelly Criterion all depend on the probability estimates and Combination Factors you use.

Multiplying the individual probabilities assumes that the selections are independent of each other.

Selections in the same event can be correlated. For example, Over 2.5 Goals and Both Teams to Score are related outcomes because matches with more goals are more likely to satisfy both selections.

The Combination Factor allows you to account for this correlation when calculating the combined probability and fair odds of your Bet Builder.

The Combination Factor is used to adjust for the correlation between selections in the same Bet Builder.

A factor of 1.00 represents no adjustment. A factor above 1.00 increases the combined probability, while a factor below 1.00 decreases it.

The first selection normally has no Combination Factor. Each additional selection can have its own factor based on its relationship with the selections already included in the Bet Builder.

The calculator does not determine the correct Combination Factor for you. It allows you to apply your own assumption and see how it affects the combined probability and fair odds.

Use a factor above 1.00 when selections are positively correlated and are more likely to occur together than they would if they were independent. Use a factor below 1.00 when selections are negatively correlated.

For example, two selections that both depend on the same team scoring may be positively correlated.

Estimating the strength of a correlation can be difficult, so use Combination Factors cautiously and avoid being over-confident in your estimates. A Combination Factor can only be as precise as the assumption behind it.

The calculator shows you what your assumption implies; it does not determine whether the assumption is correct.

Bet Builder odds may include a higher bookmaker margin than the odds offered on individual markets.

Use our tool to calculate your fair odds for the Bet Builder. You can then enter the bookmaker's odds and compare them with your calculated fair odds. If the bookmaker's odds are higher than your fair odds, the price may represent value based on your estimated probability and Combination Factors.

The tool also shows Edge to indicate the expected advantage of the bookmaker's price based on your combined probability. It also shows the Kelly Criterion, which uses the same estimated edge to calculate the proportion of your staking base that could be allocated to the bet. Your Proposed Stake is then calculated from the Kelly Criterion and your selected staking settings.

A positive Edge does not guarantee that the Bet Builder will win. Your estimated probabilities or Combination Factors may not accurately reflect the true likelihood of the outcomes, and even if your estimates are well-founded, individual bets can still lose. If your estimates and Combination Factors are sound and you consistently take Bet Builders with positive Edge, you would theoretically expect to make a profit over the long term.

The Kelly Criterion is a staking method that uses your estimated probability and the available odds to calculate how much of your staking base to risk when an edge exists.

In this tool, the Kelly Criterion is shown as a percentage. The Proposed Stake converts that percentage into a monetary amount based on your Kelly staking settings. You can choose between a fixed multiplier or fixed bankroll, and select the Kelly fraction you want to use, such as full Kelly or half Kelly.

Kelly staking does not guarantee a profit or a winning bet. Because the calculation depends on your estimated probabilities and Combination Factors, the resulting stake is only as reliable as those estimates. Even with well-founded estimates, individual bets can still lose and results can vary significantly.