Free betting calculator
No-vig fair odds calculator
Enter both sides of a two-way market to estimate fair odds and win probabilities after removing the quoted margin. The calculator uses proportional normalization—not an independent prediction of the game.
Enter positive odds with a plus sign or number, and negative odds with a minus sign.
Fair probabilities use proportional vig removal; fair odds are rounded to whole numbers. With a shared push or refund outcome, probabilities are conditional on a decided bet.
What the result means
Use the number as an estimate
Sportsbook prices usually imply probabilities totaling more than 100%. That excess is the market overround. Dividing each side by the combined implied probability produces a proportional no-vig estimate; it does not reveal the true chance of winning or the sportsbook’s actual revenue.
Two sides at -110 each imply 52.38%, or 104.76% combined. Normalizing both sides returns an estimated 50.00% fair probability for each.
How to use it
Check the inputs before the output
- 01
Take both prices from one sportsbook at the same time, matching the event, line, period, and settlement rules.
- 02
Check the market overround, then read the estimated probability and fair price for each side.
- 03
Compare a current offer for the same selection with its fair price, keeping the probability assumption in view.
Important limits
What the calculator cannot verify
- Proportional normalization is one estimation method, not objective truth.
- Pushes require a conditional interpretation; quarter-lines with partial wins and losses need a different model.
- Do not omit the draw from a three-way market or combine prices for different lines.
By Edge Team · Updated
Worked example: remove the vig from -120 and +100
Imagine a two-way market with no draw or push: Side 1 costs -120 and Side 2 pays +100. These are hypothetical prices, not a current game or recommendation.
| Measure | Side 1 | Side 2 |
|---|---|---|
| Quoted American odds | -120 | +100 |
| Implied probability | 54.55% | 50.00% |
| No-vig estimate | 52.17% | 47.83% |
| Fair American odds, approximately | -109.09 | +109.09 |
First convert each price: 120 ÷ 220 = 54.5455%, and 100 ÷ 200 = 50%. Their sum is 104.5455%, giving an overround of about 4.55 percentage points above 100%. Then divide each probability by that sum: 54.5455 ÷ 104.5455 = 52.1739%, and 50 ÷ 104.5455 = 47.8261%. Calculations use unrounded values.
The two estimates now add to 100%. This preserves the ratio between their implied probabilities; it is not the same as subtracting half the overround from each side. Use the odds-to-probability converter to check the first step.
A better price can still be below fair value
Keep looking at Side 2, whose estimate is 47.8261% and fair price is about +109.09. Another sportsbook offering +105 pays more than +100, but still less than this illustrative fair price. For a hypothetical $100 stake, EV = (win probability × winning profit) − (loss probability × stake).
- Side 2 at +105: (11/23 × $105) − (12/23 × $100) = −$1.96 estimated EV.
- Side 2 at +115: (11/23 × $115) − (12/23 × $100) = +$2.83 estimated EV.
Neither calculation proves an edge exists. If Side 2's real win probability were 46% instead, the +115 price would have EV of −$1.10 per $100. Try different assumptions in the expected value calculator before treating a small difference as meaningful. A positive estimate does not guarantee profit, even over many bets.
Overround is not the sportsbook's realized hold
This tool measures the excess implied probability in the quoted prices. It cannot tell you how much money the operator actually kept. Realized results depend on the stakes accepted and payouts made; the UK Gambling Commission's yield guidance illustrates that transaction-based accounting distinction. Its reporting rules are specific to that jurisdiction.
Take both prices from one book to examine that book's market. Combining the best price for each side across different books produces a composite, not any one sportsbook's margin. If the sum falls below 100%, investigate the matching rules and execution risks with the arbitrage calculator; do not assume a risk-free return.
Which bets fit a two-way no-vig calculator?
- Same market: match the event, exact spread or total, time period, and overtime rules. Over 24.5 and under 25.5 are not opposite sides of one market.
- Three-way markets: home win, draw, and away win require all three prices. Entering only the two teams does not recover their unconditional win probabilities.
- Shared pushes: if both sides refund on the same result, interpret the normalized estimates as conditional on the bet being decided. The quoted pair does not supply the push probability.
- Partial settlements: quarter-line handicaps can half-win or half-lose. Use the Asian-handicap settlement examples rather than treating them as simple win/lose bets.
With a push, unconditional EV needs separate win, loss, and push probabilities; a fully refunded push contributes zero profit. Check the operator's rules, not just the market name. For example, Betfair's sportsbook rules distinguish products and settlement conditions. Those rules are not a substitute for your own operator's terms.
Why fair-odds methods can disagree
Proportional removal applies the same scaling factor to both implied probabilities. It does not account for different margin allocation between favorites and longshots. Research by Clarke, Kovalchik, and Ingram compares normalization with other approaches and identifies that limitation. A different method can return different fair prices from the same inputs.
Start with a clearly defined reference market, keep its timestamp, and separate that estimate from the price you can actually receive. Use odds comparison to compare matching offers, or review current NBA odds. This free calculator normalizes one pair of prices; it is not the same as Edge's cross-book grading methodology. Set limits before betting, never chase losses, and use our responsible-gambling resources if needed.
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