Bonus Bet Calculator: Convert Free Plays to Guaranteed Cash
A bonus bet or free play pays winnings only, not the stake, which changes the math completely. You cannot evaluate a free play the same way you evaluate a cash bet. Hedging it against an opposing outcome locks in a portion of the face value as guaranteed profit no matter what happens. This calculator sizes the hedge and shows exactly what percentage you convert.
Why free plays need their own calculator
On a regular $100 bet at +200, a win returns $200 profit plus your $100 stake - $300 total. On a $100 free play at +200, a win returns only $200 profit. The stake is forfeited either way. That distinction forces a completely different hedging calculation.
Conversion rate is the metric that matters: guaranteed cash retained as a fraction of the free play face value. Industry standard is 70% or better. Below that, you either accepted too much juice on the hedge or used free play odds that were too short.
The hedge works because you place the free play on a longer shot, collect a large payout if it hits, and offset with a cash bet on the other side at a tighter price. One leg always wins; your profit is the gap between what you win and what you risked in cash.
How the conversion math works
Hedge stake = Free play amount x (Free play decimal - 1) / Hedge decimal. That formula aligns both outcomes to a similar profit. The calculator runs this automatically.
Longer free play odds improve conversion because the win payout is larger, funding a larger hedge. At -110 both sides you convert roughly 50%. At +200 free play against -200 hedge you approach 67-70%. At +500 the conversion can reach 80% or above.
- -110 free play vs -110 hedge: roughly 48-52% conversion
- +200 free play vs -200 hedge: roughly 67-70% conversion
- +500 free play vs -500 hedge: roughly 80-83% conversion
Step by step: using this calculator
Read the promo terms before starting. Many free plays have minimum odds requirements, specific market restrictions, and expiration windows. A hedge that violates terms gets voided and you lose the free play with no return.
The hedge odds matter significantly. Shop for the tightest available price on the opposing side. Every 10 cents of extra juice on the hedge leg costs roughly 2-3% conversion.
- Enter Free Play Amount - the face value shown in your promo balance.
- Enter Free Play Line - the odds you plan to use for the free play side.
- Enter Hedge Line - best available odds on the opposing outcome at another book.
- Read Hedge Bet, $ Profit, and % Profit to confirm conversion before placing.
Worked example: $100 free play at +250, hedge at -240
Free play at +250 (decimal 3.50). Hedge at -240 (decimal 1.417). Hedge formula: $100 x (3.50 - 1) / 1.417 = $176 hedge stake.
If free play side wins: collect $250 profit on the free play, lose $176 cash hedge, net = +$74. If hedge wins: $176 at decimal 1.417 returns $73.50 profit on cash. Both outcomes land near $73-74 profit.
Conversion: $73 / $100 = 73%, clearing the 70% benchmark. That result degrades fast if the hedge line moves - refreshing both lines before placing is essential.
Hedge stake
$208
Conversion rate
71%
Guaranteed profit
+$71
Mistakes that crater conversion
Using the same book for both legs is a common error. Most promotions explicitly prohibit using a bonus bet and a cash bet on opposite sides of the same event at the same book. Use a second book for the hedge.
Waiting to place the hedge is risky. Lines move, and a 10-cent shift on the hedge can cost 3-4% conversion. Once you commit to a free play price, execute the hedge immediately.
Missing the minimum odds clause gets the free play voided without return. If the promo requires +100 or longer and your free play line is -120, the bet does not count as a qualifying free play.
What most calculator pages skip
OddsGuard works on any device with no account required. When you are chasing the best hedge line, the extension shows prices across 75+ books in real time so you find the tightest opposing odds rather than settling for whatever one book happens to offer.