Fair Odds Calculator
The fair odds behind any sportsbook market are the prices that would exist with no margin baked in. Enter both sides and we'll show you the true, fair value — the break-even line where neither side has an edge.
What "fair odds" actually means
Fair odds reflect the true probability of an outcome — the price you'd pay (or receive) if the sportsbook took no margin. In a perfectly fair market, the two sides' implied probabilities would sum to exactly 100%.
Real sportsbook lines sum to 102–110% because the book builds in a margin. Strip that margin out — proportionally across both sides — and you're left with the fair odds.
Why fair odds matter
- It's your benchmark. Every +EV decision is your price vs. the fair price.
- It exposes weak boosts. Many sportsbook boosts are still worse than fair — fair odds show that instantly.
- It tells you the true win rate. You need to win at the fair probability to break even.
- It's market-derived, not opinion. Fair odds come from the market itself, not a model or a tout.
Worked example — Bills vs. Chiefs moneyline
- 1Posted price: Bills +120 / Chiefs −140
- 2Bills implied prob: 100 / (120 + 100) = 45.45%
- 3Chiefs implied prob: 140 / (140 + 100) = 58.33%
- 4Sum: 103.78%Book hold = 3.78%
- 5Fair Bills prob: 45.45 / 103.78 = 43.79%Fair price ≈ +128
- 6Fair Chiefs prob: 58.33 / 103.78 = 56.21%Fair price ≈ −128
Frequently asked questions
What is a fair odds calculator?+
A fair odds calculator takes a sportsbook's two-sided price and strips out the book's margin to return the vig-free price — the true odds that reflect the real probability of each outcome. It's the benchmark every +EV decision is measured against.
How does this fair odds calculator work?+
Enter the American odds for both sides of a two-way market (moneyline, spread, total, prop). The calculator converts each price to implied probability, sums them, then divides each by the total to get the fair (vig-free) probability — and converts that back to American odds.
What are fair odds in sports betting?+
Fair odds reflect the true probability of an outcome — the price you'd get if the sportsbook took no margin. In a perfectly fair two-way market, the two sides' implied probabilities sum to exactly 100%.
How do I calculate fair value odds?+
Take a sharp book's two-sided price (Pinnacle is the gold standard), convert each side to implied probability, then divide each by the sum of both. Convert that fair probability back to American odds. This calculator does it instantly.
Are fair odds the same as true odds or no-vig odds?+
Yes — fair odds, true odds, no-vig odds, no-juice odds, and devigged odds all describe the same number: the price with the sportsbook's margin removed. Different tools call it different things, but the math is identical.
How accurate is the fair odds calculator?+
The math is exact — fair odds are derived from the two prices you enter. Accuracy comes from your inputs: devigging a sharp book like Pinnacle or Circa gives a fair price within ~1% of the true probability. Devigging a soft book reflects that book's balancing, not market consensus.
Why don't sportsbooks just post fair odds?+
Because vig is how they make money. A typical US book runs a 4–6% hold on moneylines and 6–10% on player props. The fair price is the break-even line; everything above that hold is the book's profit.
How do I use fair odds to find +EV bets?+
Compare your sportsbook's price to the fair price from a sharp book. If your book pays more than fair, you have positive expected value. Plug both numbers into our EV calculator to see the exact edge percentage and long-run profit per bet.
Can I use this calculator for player props and three-way markets?+
It works perfectly for any two-sided market — over/under at the same line, yes/no props, two-way moneylines. For three-way markets like soccer 1X2 or draw-no-bet, the multiplicative devig is still a reasonable approximation but more advanced methods (Shin, power) can be more accurate.
One step further
The Bet Analyzer compares your sportsbook's price to live fair odds from multiple books — and returns a single A–F grade plus edge % and expected value.