No-Vig & Fair Odds

Every line a sportsbook posts is padded with a hidden margin called the vig. Strip it out and you're left with the line's true probability — the number you need before you can spot a +EV bet.

What the vig actually is

Why is a 50/50 coin-flip market priced at −110 on both sides instead of an even +100? Because the sportsbook charges a commission. That commission — the vig (short for vigorish), also called the juice — is how books make money no matter who wins.

At −110/−110, the book is implying each side has about a 52.4% chance. But two outcomes can't both be 52.4% likely — that adds up to 104.8%. That extra 4.8% is the vig. It's a phantom probability the book sells to itself, and it's the reason naive bettors slowly bleed out even on 50/50 guesses.

Step 1 — Convert odds to implied probability

American odds convert to an implied probability like this:

Take a real market — say a tennis match priced at −130 for the favorite and +110 for the underdog:

Side	Odds	Implied probability
Favorite	−130	130 / 230 = 56.5%
Underdog	+110	100 / 210 = 47.6%
Total	—	104.1%

The two sides sum to 104.1%. That 4.1% overage is the vig on this market.

Step 2 — Divide out the vig

To get the fair, no-vig probability for each side, divide each implied probability by the total:

Now they sum to a clean 100%. The favorite's true probability isn't 56.5% — that included the book's cut. It's 54.3%. That's your fair number.

Step 3 — Convert fair probability back to odds

Flip the probability back into American odds to get the fair price:

Our underdog's fair probability of 45.7% converts to roughly +119. So the genuinely fair price on that dog is +119 — not the +110 the book posted. If another sportsbook is offering +130 on the same underdog, you've found a +EV bet: you're getting paid +130 for something worth +119.

Why this works best with Pinnacle

Removing the vig only gives you a true probability if the line you started with was sharp. Garbage in, garbage out. That's why serious bettors devig Pinnacle specifically:

• They take the biggest bets in the world. Limits in the six figures mean sharp money pounds any mispricing until it's gone.
• They don't limit winners. Most US books ban or throttle anyone who wins. Pinnacle welcomes them — so their prices are sharpened by the smartest bettors alive.
• Low margin. Pinnacle runs thin vig to begin with, so there's less distortion to remove and the fair number is more reliable.

Devig Pinnacle, and you have the market's best estimate of the truth. Compare it against the softer US books — DraftKings, FanDuel, BetMGM, Caesars — and the gaps between them are your edges.

The catch: doing it live, everywhere, all at once

The math on one market takes thirty seconds. The problem is that there are thousands of markets across a dozen books, the lines move every few seconds, and a +EV gap can vanish before you've finished typing it into a calculator. Devigging by hand is fine for learning the concept and impossible as a strategy.

That's exactly the job Iron Marker automates: pull Pinnacle's line, remove the vig, compare it to every US book in real time, and surface only the bets where the price beats fair value — with the Kelly stake already calculated.

Iron Marker is an analytics tool, not a sportsbook, and this guide is educational — not betting or financial advice. Odds shown are illustrative. Must be 21+. Problem gambling? Call 1-800-GAMBLER.