Enter your bonus bet amount and the American odds you plan to use. The calculator returns the expected cash-equivalent value, the conversion rate (cents on the dollar), and a verdict on whether the odds you picked are in the optimal range.
Most sportsbook "free bets" (also called bonus bets, site credit, or promo bets) pay only the profit if the bet wins, not the stake. A $100 free bet at +200 wins $200 (not $300 like a cash bet would). If it loses, you get nothing. The math: expected value = probability of winning × profit-only payout.
Because the stake doesn't return, free bets are worth significantly less than face value. A $100 free bet typically converts to 60–75 cents on the dollar at sensibly chosen odds. Cash bonuses that return stake on a win are nearly identical to cash and convert at ~100% of face value (minus the small vig you'd pay anyway).
Counter-intuitively, you want to use a free bet on a longer-shot price (a +200 to +400 underdog), not on a -200 favorite. The reason: a free bet at -200 wins you only $50 profit; the same free bet at +300 wins $300 profit. Even though the favorite hits more often, the dollar-weighted EV is higher on longer prices.
The optimal range for a $100 free bet (stake-not-returned) is typically +200 to +500. Below +150 the lower payout drags conversion rate down; above +700 the win probability gets too low to capture most of the value in any given attempt. A small portfolio of bonus bets on different longshots tends to converge to ~70% conversion if odds are well-chosen.
If you have a free bet AND the option to hedge the other side at a different book, you can lock in a guaranteed conversion. Use our Arbitrage & Hedge Calculator to size the hedge. Sportsbook welcome promos — deposit matches, $1000-back insurance, free-bet ladders — can deliver 4-figure value if hedged systematically across multiple operators on the same market.