De-vigging Odds: How to Find the True Probability

Every price a bookmaker offers has a hidden tax baked in — the vig (also called juice or margin). If you read odds at face value, you're reading an inflated picture of how likely things are. De-vigging strips that tax out so you can see the bookmaker's true estimated probability.

Step 1: Odds → implied probability

For decimal odds, implied probability = 1 ÷ odds.

• Odds 2.00 → 1 ÷ 2.00 = 50%
• Odds 1.80 → 1 ÷ 1.80 = 55.6%
• Odds 2.10 → 1 ÷ 2.10 = 47.6%

Step 2: Notice the total is over 100%

Take a two-way market priced 1.90 / 1.90:

• 1 ÷ 1.90 = 52.6% each
• Total = 105.2%

That extra 5.2% is the vig — the bookmaker's margin.

Step 3: Remove the vig (normalise to 100%)

Divide each implied probability by the total.

• Side A: 52.6 ÷ 105.2 = 50.0%
• Side B: 52.6 ÷ 105.2 = 50.0%

So 1.90/1.90 is genuinely a coin flip — the 52.6% was inflated by margin.

A lopsided example

Market: Favourite 1.40, Underdog 3.00.

• Implied: 71.4% and 33.3% → total 104.7%
• De-vigged: 68.2% and 31.8%

The honest read is ~68/32, not the 71/33 the raw prices suggested.

Why this matters

De-vigging gives you a baseline: the market's best estimate of the true probability. You only have a value bet when your estimate is meaningfully higher than the de-vigged market probability. Without removing the vig first, you'll systematically overestimate how often things should happen — and overpay.

FAQ

What is the vig? The bookmaker's built-in margin — the reason implied probabilities add up to more than 100%.

How do I calculate implied probability? For decimal odds, divide 1 by the odds (e.g. 1 ÷ 2.50 = 40%).

Does a de-vigged probability mean it will happen? No — it's an estimate of likelihood, not a guarantee. Bet responsibly and only what you can afford to lose. WildlyPlay — read the real number, not the marketed one.