Strip the juice.
See the true odds.
Sportsbooks bake a margin into every line. Enter both sides of a market and this removes the vig to show the fair probability the book is actually pricing.
01What "de-vig" actually does
A sportsbook quote isn't a clean probability — it's a probability plus the book's cut. Convert both sides of a market to implied probability and they sum to more than 100%. That overround is the vig. De-vigging rescales each side so they sum back to 100%, leaving the book's true read on the matchup.
02Why it matters
The de-vigged number is the price you compare everything else against. If one book's fair line on a side is better than another book's posted line, that gap is your edge. It's also how you sanity-check a model: if your number and the no-vig market number disagree, one of you is wrong — and the market is right more often than not.
03The method here
This uses multiplicative (proportional) de-vigging — each side's implied probability is divided by the total overround. It's the standard approach and works cleanly for two-way and three-way markets alike. For lopsided favorites, proportional de-vig slightly understates the favorite versus more advanced methods (Shin, power), but for everyday line-shopping it's the right tool.
No-vig calculator FAQ
The vig — short for vigorish, also called the juice or the hold — is the margin a sportsbook builds into its odds. It's how the book makes money regardless of which side wins. When you add up the implied probability of both sides of a market, the total comes out above 100%; that extra slice is the vig.
A standard two-way market priced at -110 on both sides carries roughly 4.5% vig. The bigger the number, the more the book is charging you to place the bet.
De-vigging removes the book's margin from a price to reveal the fair probability underneath. Instead of two sides that sum to 104.5%, you rescale them to sum to exactly 100% — leaving the market's true read on the matchup with the house cut stripped out.
The result is called the no-vig price or fair price. It's the number sharp bettors compare everything against.
Convert each side of the market to implied probability by taking 1 divided by its decimal odds. Add those probabilities together to get the overround — a number above 1.0. Then divide each side's probability by that total. The results now sum to 100% and represent the fair, vig-free probabilities.
This tool uses that proportional method automatically — enter both sides and it does the math for two-way or three-way markets.
It's your benchmark for finding value. If you can bet a side at odds better than its fair no-vig price — whether at another book or because your own read differs from the market — that gap is your edge. Without removing the vig first, you're comparing prices that all secretly include the house margin.
Once you have a fair probability, the Kelly calculator can turn that edge into a stake size.
For everyday line-shopping, yes. Proportional (multiplicative) de-vigging is the standard method and works cleanly across two-way and three-way markets. On heavily lopsided favorites it slightly understates the favorite compared with more advanced models like Shin or the power method, but the difference is small and rarely changes a betting decision.