What the bookmaker margin costs you
How to calculate a sportsbook's margin from its prices, what a typical margin is, and why it matters more than any bonus.
By the Sportsbooks Editorial Team · Updated October 27, 2026
Every price a sportsbook offers contains a built-in edge called the margin (also overround, vig or juice). It is the main reason most bettors lose over time, and the single biggest difference between a good sportsbook and an average one. Margins move with every price change, so check them yourself on the markets you bet on most.
How the margin is built into prices
Take a coin toss. The fair price for heads is 2.00 and for tails 2.00. Their implied probabilities, 50% each, add up to exactly 100%.
A sportsbook would offer something like 1.91 and 1.91 instead. Each implies 52.4%, and together they add up to 104.7%. The extra 4.7% is the margin: on balanced action the sportsbook keeps about that share of the money staked, whichever side wins.
How to calculate it
- Take the decimal odds of every outcome in one market.
- Work out 1 ÷ odds for each.
- Add them up and subtract 1.
Example, a football match result: home 2.10, draw 3.40, away 3.50.
| Outcome | Odds | 1 ÷ odds |
|---|---|---|
| Home | 2.10 | 0.476 |
| Draw | 3.40 | 0.294 |
| Away | 3.50 | 0.286 |
| Total | 1.056 |
The margin is 5.6%. Our margin calculator does this for any market and also shows the fair odds without the margin.
What is a typical margin?
- Two-way markets (moneylines, spreads, totals): about 4% to 5% is common, under 3% is sharp.
- Three-way football match results: often 5% to 8%.
- Player props, futures and niche leagues: frequently well above 10%.
Why a small difference matters
Margins compound. Over 500 bets of 10, a sportsbook taking 3% instead of 6% leaves roughly 150 more in your account on the same picks, before any skill comes into it. Betting the same selections at the lowest-margin sportsbook available to you is the easiest edge there is.
That is why every review on this site reports the average margin we measured on match-result markets across a four-week sample. See how we rate sportsbooks.
Frequently asked questions
How do you calculate a bookmaker's margin?
Divide 1 by each outcome's decimal odds, add the results and subtract 1. Prices of 1.91 on both sides of a market give 0.5236 + 0.5236 = 1.047, a margin of 4.7%.
Is the margin the same as the vig or juice?
Yes, in everyday use. Margin, overround, vig, vigorish and juice all describe the share a sportsbook builds into its prices. Strictly, the vig is the margin expressed as a share of the money staked, which is slightly lower than the overround.
Why do margins differ between markets?
Sportsbooks price popular, liquid markets such as Premier League match results or NFL spreads more tightly than niche markets, props and live bets, where their risk and uncertainty are higher.