Betting calculator
No-Vig Fair Odds Calculator
Remove bookmaker margin from a simple two-outcome market and estimate the no-vig fair probabilities and fair decimal odds.
Enter two decimal prices
Optional labels make the results easier to read.
| Outcome | Implied probability | No-vig fair probability | No-vig fair odds |
|---|---|---|---|
| Outcome A | 52.36% | 50.00% | 2.00 |
| Outcome B | 52.36% | 50.00% | 2.00 |
The margin is removed by scaling each implied probability by the total book percentage.
No-vig fair odds formula
The calculator first converts each price into implied probability, then divides each implied probability by the total book percentage.
Implied probability = 1 / decimal odds
Book percentage = implied probability A + implied probability B
Overround = book percentage - 1
Fair probability = implied probability / book percentage
Fair odds = 1 / fair probability
Worked example
If both outcomes are priced at 1.91, each side has an implied probability of about 52.36%. Together they add up to 104.71%, which is a 4.71% overround. After removing the margin, each side is estimated at 50.00%, which is fair odds of 2.00.
Responsible use
No-vig odds are an educational estimate. Real markets may include commission, void rules, liquidity, each-way terms, changing prices or other conditions. No-vig odds do not prove that a bet is good value and do not guarantee profit.
For the plain-English explanation behind the calculation, read What Are No-Vig Fair Odds?.
Understand the result
How to interpret this calculator
Betting Maths calculators are designed to show the arithmetic behind the inputs you provide. A calculated return, probability, liability or expected value is not a prediction that an event will happen.
Check the assumptions
Results depend on the odds, stakes, commission, place terms or probability estimates entered. If the inputs change, the result changes.
Reproduce the maths
Our methodology explains the core formulas, rounding approach and limitations used across the calculator library.
Read the calculation methodologyUse the result educationally
Real settlement can also depend on bookmaker or exchange rules, non-runners, voids, liquidity, price movement and promotional terms.