How we value sportsbook bonuses
Sportsbooks advertise a big headline number. We estimate what an offer is actually worth to a normal bettor, so you can compare them apples‑to‑apples. Here's exactly how — and which inputs you can change yourself on the rankings page.
The core idea: a bonus bet isn't cash
When you stake a bonus bet and it wins, you keep the winnings but not the stake. So its value as a fraction of face value depends on the odds you place it at:
EV fraction = 1 − 1/d (d = decimal odds, for a roughly fair bet)
- Even odds (+100, d = 2): 50% of face value
- +200 (d = 3): 67%
- +300 (d = 4): 75%
A $100 bonus bet is worth roughly $50–$80 depending on where you place it — never face value. We default to 70% (a sensible bettor at around +230). That single number is the biggest lever, so it's a slider.
The formula for each offer type
- Guaranteed bonus bets ("bet $5, get $365"):
bonusAmount × conv − qualifyingBet × 4.5%. The 4.5% is the sportsbook's hold on the small qualifying bet you must place. Near‑guaranteed — you get the bonus bets regardless of the result. - First‑bet safety net ("first bet up to $1,500 back if it loses"):
P(lose) × yourFirstBet × conv. It only pays if you lose, and scales with how much you risk — so the "real value" uses a typical first bet, while "best case" uses the full cap (and assumes a loss). - Profit boost ("double your winnings ×10"):
numBets × stake × boost × (1 − 1/d). Almost entirely stake‑dependent, so it's the softest estimate.
The assumptions (all adjustable)
- Bonus‑bet conversion — 70%. An assumption about the odds you bet at. 50% (even) to 80% (longshots).
- Sportsbook hold — 4.5%. Industry‑average vig on a standard market; only affects the tiny qualifying‑bet cost.
- First bet loses — 52%. Roughly even, leaning slightly to a loss. Drives safety‑net value.
- Reference first bet — $100. A realistic sign‑up bet, used for the "real value" of safety nets.
- Profit‑boost stake — $25/bet. A realistic per‑bet stake for boost offers.
What's solid: that bonus bets aren't cash (the 1 − 1/d principle) and the hold figure. What's an estimate: the conversion, loss rate, and reference stakes. They're tuned to what a normal person realistically gets — between the book's face‑value hype and optimal "matched betting" extraction.
Frequently asked questions
Are these numbers exact?
No — they're a consistent model, not a guarantee. The bonus-bet conversion is the biggest assumption; we default to 70% (a sensible bettor placing at moderate odds). You can adjust it and the other assumptions with the sliders on the rankings page.
Why 70% for a bonus bet?
A bonus bet returns winnings but not the stake, so its value as a fraction of face is 1 − 1/odds: about 50% at even odds, ~67% at +200, ~75% at +300. 70% reflects placing them around +230.
21+ (check your state). Informational only, not betting advice. Gambling problem? Call 1‑800‑GAMBLER.