No-vig fair odds calculator
Enter the odds for each side of a market. The calculator shows the bookmaker's margin and the fair odds once it is removed.
19+ in most of Canada (18+ in Alberta, Manitoba and Quebec), 21+ in most US states. A calculator shows what a bet pays, not how likely it is to win. Free help: 1-800-GAMBLER (US), ConnexOntario 1-866-531-2600 (Ontario), 211 (Alberta). More help.
The formula
implied probability = 1 ÷ decimal odds, fair probability = implied ÷ sum of implied, fair odds = 1 ÷ fair probability, hold = 1 − 1 ÷ sum of implied.
Worked example
A -200 favourite against a +170 underdog: implied 66.67% + 37.04% = 103.70%. Fair odds −180 and +180 (64.29% / 35.71%). The book holds 3.57%.
Margin on common lines
| Line | Sum of implied | Hold | Fair odds |
|---|---|---|---|
| -105 / -105 | 102.44% | 2.38% | +100 / +100 |
| -110 / -110 | 104.76% | 4.55% | +100 / +100 |
| -115 / -105 | 104.71% | 4.50% | −104 / +104 |
| -120 / +100 | 104.55% | 4.35% | −109 / +109 |
| -200 / +170 | 103.70% | 3.57% | −180 / +180 |
| -300 / +240 | 104.41% | 4.23% | −255 / +255 |
Proportional (multiplicative) method. Books often shade more margin onto the longshot, so other methods give slightly different fair odds on lopsided lines.
Questions
What is vig?
The bookmaker's margin built into the odds, also called juice. On a -110/-110 line the two sides imply 104.76% together; the extra 4.76% is the overround, and the hold is 4.55% of all money staked.
How do you remove the vig?
Convert both sides to implied probabilities, add them, and divide each by the total. The results add up to 100% and convert back to fair odds.
What are fair odds used for?
Comparing a price with the market: if a book offers better than the fair odds from a sharp market, the bet has positive expected value at that price.
What is the difference between overround and hold?
Overround is how far the implied probabilities exceed 100%. Hold is the share of total stakes the book keeps if action is balanced: 1 − 1 ÷ (sum of implied probabilities).