Canada · Sports betting · Free tool
Sportsbook margin calculator
Enter a sportsbook’s odds on every outcome of a market to see how much it keeps, the fair odds with its margin removed, and, with a second book’s odds, which one pays more on each outcome.
Sportsbook margin calculator
Sportsbook A keeps
Payout 95.5%4.55%
Sportsbook A keeps about $4.55 of every $100 bet on this market, on average
- Overround (A)
- 4.76%
- Payout rate (A)
- 95.45%
- Book B keeps
- 5.26%
- Payout rate (B)
- 94.74%
- Fair odds, margin removed (A)
- +100 / +100
Sportsbook A keeps 0.72% less of every bet
Outcome by outcome
| Outcome | A | B | Better | Extra |
|---|---|---|---|---|
| 1 | -110 | -125 | Book A | +$10.91 |
| 2 | -110 | +100 | Book B | +$9.09 |
| 3 | — | — | — | — |
Margin assumes bets follow the fair probabilities (proportional method). Outcomes are in the order you entered them. “Extra” is how much more the better price returns on your stake if that outcome wins.
How the calculator works
A sportsbook never offers fair odds. Add up the implied probabilities of every outcome in a market and you get more than 100%: the excess is the overround, and it’s how the book makes money whoever wins. At −110 on both sides of a spread, each side implies 52.4%, together 104.8%, and the book keeps about 4.5% of everything staked on that market over time.
Enter the odds a sportsbook offers on each outcome, in American, decimal or fractional format, and the calculator shows how much it keeps, the share it pays back, and the fair odds with the margin removed. Add a second sportsbook’s odds on the same game to see which one keeps less, and which pays more on each outcome. Comparing prices like this, called line shopping, is the simplest way to cut what betting costs you; in Canada it’s most useful if you’re in Ontario, where many registered sportsbooks compete, or if you want to see how a provincial site’s prices compare.
Typical margins
What a sportsbook keeps on common price pairs, computed with the same formula as the calculator.
| Market and prices | Overround | Book keeps | Pays back |
|---|---|---|---|
| Spread or total at −110 / −110 | 4.76% | 4.55% | 95.45% |
| Spread or total at −105 / −105 | 2.44% | 2.38% | 97.62% |
| Moneyline at −150 / +130 | 3.48% | 3.36% | 96.64% |
| Moneyline at −160 / +120 | 6.99% | 6.54% | 93.46% |
| Soccer 1X2 at 2.10 / 3.40 / 3.60 | 4.81% | 4.59% | 95.41% |
Frequently asked questions
What is a sportsbook margin?
The difference between the odds a sportsbook offers and fair odds. Add up the implied probabilities of every outcome and you get more than 100%: the excess is the overround. At −110 on both sides, the implied probabilities add up to 104.76%, and the book keeps about 4.55% of everything staked on that market over time.
How is the hold calculated?
Hold = 1 − 1 ÷ (sum of the implied probabilities), which is what the book keeps if bets follow the fair probabilities. The payout rate is the rest: 1 ÷ (sum of the implied probabilities). The calculator removes the margin proportionally to get the fair odds.
What is a normal margin for a sportsbook?
About 4.5% on a standard −110/−110 spread or total. Moneylines and props usually carry more. Pinnacle says its prices average a 2% margin against an industry average of about 6%, and across Ontario’s regulated market, sportsbooks kept 6.81% of cash wagers in 2025–26, according to iGaming Ontario.
Why compare two sportsbooks?
Because the same bet pays differently at different books. Taking the better price on each bet, called line shopping, is the simplest way to cut what betting costs you; the calculator shows how much more each outcome would return on your stake at the better book.
Does a lower margin mean I will win?
No. It means you lose less on average. Even at a 2% margin, a bettor who picks at random loses about 2% of everything staked over time, before any variance.
Keep reading
Sources
We verify facts against primary sources (regulators, court records, operators’ own terms) wherever possible.
- Monthly market performance report (data tables to August 31, 2026) — iGaming Ontario , 2026-09-23
- Pinnacle’s margin compared with the industry (help centre article) — Pinnacle , updated 2026-03-30