The Expected Value calculator helps you determine whether a promotion that triggers conditionally (e.g., "Bonus bet if your team scores first") is worth taking. It calculates the average profit you can expect across many repetitions of the bet.

When to use it

Use the Expected Value calculator when evaluating promotions like:

• "Get $50 bonus bet if your team scores first"
• "Cash back as bonus bet if you lose by less than 7 points"
• "Bonus bet refund if the match goes to extra time"
• Any promotion where the bonus only triggers under specific conditions

How it works

The calculator balances your back bet with a lay bet at the exchange, then calculates two scenarios:

1. Miss SR (Bonus doesn't trigger): Your net profit from the balanced matched bet
2. Hit SR (Bonus triggers): Your net profit from the matched bet PLUS the value of the bonus bet you receive

It then weights these outcomes by their probabilities to give you an Expected Value (EV). Positive EV means the promotion is profitable in the long run, but not necessarily every time.

Understanding the inputs

Bet details

• Stake: The amount you're betting at the bookmaker.
• Back Odds: The odds at the bookmaker for your selection.
• Lay Odds: The odds at which you can lay the same outcome at the exchange.
• Commission: The exchange commission on winning lay bets (typically ~5%).

Promo details

• Bonus Amount: The value of the bonus bet you'll receive if the condition triggers (e.g., $50).
• Retention Rate: What percentage of the bonus bet you expect to convert to withdrawable cash. Typically 70-80% depending on odds available.

Expected value

• Odds of Bonus Triggering (Decimal): The fair odds for the bonus condition happening. Ideally, this should be sourced from our Sportsbook index if we have a market for that condition i.e., "team scores first" odds.
• Probability of Bonus Triggering: The same as above but as a percentage. Enter either this OR the decimal odds - they sync automatically.

Understanding the outputs

The calculator provides several key values:

1. Lay Stake: The amount to lay at the exchange to balance your back bet.
2. Liability: The amount you need in your exchange account to cover the lay bet.
3. Miss SR: Your profit if the bonus condition doesn't trigger. This is typically a small loss or break-even from the matched bet.
4. Hit SR: Your profit if the bonus condition triggers. This includes the value of your bonus bet.
5. Probability of Receiving Bonus: Shows your estimated chance of getting the bonus.
6. Probability of Not Receiving Bonus: Shows the complement (1 - probability).
7. Expected Value (EV): The average profit per bet if you repeated this promotion many times. This is the most important number - positive EV means the promo is profitable.

Practical example

TAB offers "Get a bonus bet if your team scores first" on an NRL match. You're considering backing the Broncos:

• Broncos odds: 2.50 at TAB
• Broncos lay odds: 2.52 at Betfair
• Exchange commission: 5%
• Bonus amount: $50
• Expected retention: 75%
• According to our Sportsbook index, the fair odds for the Broncos to score first in this match are 2.86

Enter these values with a $50 stake:

The calculator shows:

• Lay Stake: $50.61
• Miss SR: -$1.92 (small loss if they don't score first)
• Hit SR: $35.58 (profit if they score first, including bonus value)
• EV: $11.19

With a positive EV of $11.19, this promotion is profitable. On average, each time you take this promotion, you'll make $11.19. Some times you'll make $36.88, some times you'll lose $0.62, but over many bets it averages to $11.19 profit.

Common issues

How do I estimate the probability of the bonus triggering?

Use our Sportsbook index to find markets related to the bonus condition (e.g., "team scores first" odds). If no market exists in our index, search bookmakers for a relevant market.

The Miss SR shows a loss. Is this normal?

Yes, this is expected. When you matched bet normally (without considering the promo), you typically make a small loss due to the back/lay odds difference. The promotion's bonus bet is what makes the overall EV positive. The key is whether the total EV is positive, not whether Miss SR is profitable.

Should I take every positive EV promotion?

Yes, if you have the bankroll and the EV is meaningfully positive (typically at least 5% of your stake). Over time, positive EV promotions are what generate long-term profit. However, consider the variance - low-probability high-bonus promotions can have positive EV but require a larger bankroll to weather the losses when the bonus doesn't trigger.