Estimate what a bonus bet is worth
Enter the bonus bet amount and the odds you would play: the tool works out its average value, stake not returned.
Result
- Return if the bonus bet wins (stake not returned)
- 20.00
- Implied probability
- 33.33%
- Estimated no-vig probability
- 31.45%
- Overround applied
- +6.00%
- Expected value
- 6.29
- Expected value as % of the amount
- 62.89%
Warning:
Expected value, not winnings: any single bonus bet pays its net winnings or nothing. The no-vig probability comes from removing the overround proportionally. No odds are recommended.
The tool calculates the expected value of a bonus bet whose stake is not returned: estimated no-vig probability × amount × (odds − 1). The no-vig probability comes from an overround you enter (6% by default) or, if you fill them in, from the odds of the market's other outcomes. An expected value is never a payout: any single bonus bet pays its net profit or nothing.
How does this calculator work?
The tool works out a bonus bet's net profit if it wins, then multiplies it by the estimated probability of winning once the margin is removed: that is the expected value. Everything is calculated in the browser, on every keystroke.
The result is labeled "expected value", never "winnings". It describes what a bonus bet is worth on average, not what it will pay.
The formulas applied
Three formulas are enough.
return if it wins = amount × (odds − 1)
estimated no-vig probability = (1 ÷ odds) ÷ (1 + overround)
expected value = estimated no-vig probability × return if it wins
When you enter the other outcomes' odds, the second formula is replaced by the normalized probability of the outcome played across the full market, and the overround shown becomes the market's own, measured as on the margin calculator.
A complete example
A $10 bonus bet at odds of 3.00 (+200), with a 6% overround, returns $20.00 if it wins. Its implied probability is 33.33%, or 31.45% once the margin is removed.
Its expected value comes to $6.29, or 62.89% of its amount. These are the figures the tool shows when it opens: they act as a sanity check against the table on the bonus bets page.
What the result does not say
The expected value recommends no odds. It rises with the odds, but so does the probability of getting nothing: at 10.00, a bonus bet loses about nine times out of ten. Nor does it account for the offer's terms (minimum odds, wagering requirements, expiration), which often lower its real value.
For how to read implied probability and the sportsbook's margin, the dedicated pages cover each notion.
Frequently asked questions
Is this tool free to use, with no account?
Yes. The calculation runs in the browser, with no account, no data sent and no record of the amounts or odds you enter.
Is the expected value what I will win?
No. It is an average over a large number of identical bonus bets. Any single bonus bet pays either its net profit or nothing at all. The higher the odds, the more often it pays nothing at all.
Why does the return if it wins not include the stake?
Because a bonus bet almost always comes with the stake not returned: the operator credits the net profit, amount × (odds − 1), but not the bonus amount. That is the most common rule; check it in the terms of each offer.
What are the other outcomes' odds for?
To measure the market's real overround instead of assuming it. On a three-way market (1X2), enter the odds you would play, then the other two: the tool removes the margin by proportional normalization, like the margin calculator.
Does this tool help convert a bonus bet into cash?
No. It calculates no hedge stake at another operator and teaches no conversion method. It measures the value of a bonus bet as it stands, to show why its face value is misleading.
Can I enter American odds or numbers with a comma?
Enter decimal odds: 3.00 equals +200 in American odds, and the [odds converter](ref:convertisseur_cotes) switches between formats. Comma and dot are accepted interchangeably: 3,00 as well as 3.00. To separate the other outcomes' odds, use a space or a semicolon.
Sources & method
This calculator applies the value model for a bet whose stake is not returned, as described in the academic literature, and the proportional normalization of probabilities documented on the "no-vig odds" page.
- Return if it wins = amount × (odds − 1): the bonus stake is not returned.
- Estimated no-vig probability = implied probability ÷ (1 + overround), or the normalized probability across the full market if the other odds are entered.
- Expected value = estimated no-vig probability × return if it wins; also shown as a percentage of the bonus bet amount.