Bonus Bet Calculator — Free Bet Conversion Calculator
Sportsbook promos hand out bonus bets (also called free bets) constantly, but they pay out winnings only — the stake is never returned. This calculator finds the hedge stake and guaranteed cash you lock in by betting the other side, so you know what a promo is really worth.
The formula
winnings if bonus wins = bonus × (bonus decimal − 1) ← stake NOT returned hedge stake = winnings / hedge decimal guaranteed cash = hedge stake × (hedge decimal − 1) conversion rate = guaranteed cash / bonus × 100
Worked example
A $100 bonus bet at +200 wins $200 (not $300). Hedged at -220, the hedge stake is $137.50 and you lock in $62.50 either way — a 62.5% conversion. Hedge at a nearer-to-fair -200 and the same bonus converts at 66.67%.
Getting a better conversion
- Use longer odds on the bonus side (+200 or more) — conversion rises with the underdog price.
- Find a tight market with low vig on the opposite side; see the vig calculator.
- Many calculators wrongly return the stake on a win and overstate conversion — this one doesn’t.
FAQ
Why is a bonus bet worth less than its face value?
Because a bonus or free bet doesn't return your stake if it wins — you only collect the winnings. A $100 free bet at +200 wins $200, not $300, which is why converting it to cash always recovers less than 100% of its face value.
How is the conversion rate calculated?
We size a hedge bet on the opposing side so that the cash you end up with is identical whether the free bet or the hedge wins, then express that guaranteed cash as a percentage of the original bonus amount.
What's a realistic conversion rate?
It depends entirely on how close the hedge odds are to a fair mirror of the bonus bet's odds. Tighter, closer-to-even markets convert at a higher rate; lopsided or heavily vigged matchups convert lower.
Why is a bonus bet worth less than its face value?
Because a free bet doesn’t return your stake if it wins — you only collect the winnings. A $100 free bet at +200 wins $200, not $300, so a hedge can recover at most roughly 60–75% as cash.
Is a profit boost the same as a bonus bet?
No. A profit boost raises the payout on a bet you place with your own money, so the stake is returned on a win. Use the betting odds calculator to price a boosted line.