Sportsbooks
Reading sportsbook margins: the only number that matters
Free bets are marketing. Margin is maths. A guide to calculating what a bookmaker really charges you.
James Ellery, Senior Betting Analyst · 1 October 2026 · 7 min read
Calculating the margin
Convert each price to implied probability and add both sides. At standard American odds of -110 / -110, each side implies 52.38%; together they total 104.76%, so the theoretical hold is 4.76%.
Sample the same league weekly and you get a reliable picture. Over 12 weeks, the gap between the best and worst book in our panel was 2.4 percentage points, which dwarfs the value of any welcome offer.
Why promotions rarely close the gap
A $30 bonus-bet package is a one-off. A two-point margin difference applies to every bet you ever place. If you stake $20 a week, the cheaper book can repay that promotional difference within a season.
This is why our sportsbook rankings weight pricing at 30% and promotions at 10%.
Account restrictions are part of the price
A book with excellent prices that sharply reduces your stake limit after a winning month is not functionally cheap if you cannot place the wager you priced. Limits, void rules and withdrawal friction belong in the comparison alongside hold percentage.
Frequently asked questions
What is sportsbook hold?
Hold is the theoretical margin created by the prices on all sides of a market. At -110 on both sides, the implied hold is about 4.76% before outcomes and bettor behaviour.
Is the biggest sportsbook bonus always the best offer?
No. Qualification, stake return, expiry and the book’s ongoing prices determine usable value. A smaller offer at consistently better odds can cost less over time.
Are US sports-betting winnings taxable?
The IRS says gambling winnings are taxable even when no W-2G is issued. State obligations can also apply.
Sources and verification
Play Radar is funded by affiliate commission from some operators we list. Our analysts set ratings independently using the review methodology.