Implied Probability Calculator

Turn betting odds into win probability — with vig removed.

Convert betting odds into implied win probability, and — for a two-way market — remove the sportsbook's vig to see the fair, no-vig probability for each side plus the market's hold percentage. Runs fully in your browser — nothing is uploaded.

Implied Probability Calculator features

• Convert any odds format to implied probability
• Two-way market mode removes the sportsbook's vig
• Shows the market's hold / overround percentage
• Fair (no-vig) probability for each side
• 100% free, in-browser, no sign-up

How to use Implied Probability Calculator

1. Choose single odds or a two-way market

   Convert one price into probability, or enter both sides of a market to remove the sportsbook's vig and see the fair probability.

2. Enter the odds

   Type the odds in American, Decimal or Fractional format for each side — the calculator converts automatically.

3. Read raw vs. fair probability

   In two-way mode, see each side's raw implied probability (including vig) alongside the no-vig fair probability and the market's hold percentage.

Tricks & interesting facts

Finding real value in a line

The gap between what a bet SHOULD win and what the book prices it at is where an edge lives.

• TIP Always compare your own probability estimate to the FAIR (no-vig) probability, not the raw one — the raw number always makes every bet look worse than it really is.
• FACT A 'square' or public-facing line often carries extra vig on the popular team, since the book knows recreational bettors will bet it anyway.
• TIP Shopping the same bet across a few sportsbooks and taking the best price is one of the biggest, easiest edges a casual bettor can find — completely free.

If your honest probability estimate beats the FAIR (no-vig) probability, that's a mathematically +EV (positive expected value) bet — small edges like this compound over many bets.

Frequently asked questions

What is implied probability in betting?

It's the win chance that a set of odds mathematically represents: 1 ÷ decimal odds, shown as a percentage. E.g. decimal odds of 2.00 imply a 50% win probability.

How do I calculate implied probability from American odds?

For positive odds: 100 ÷ (odds + 100) × 100. For negative odds: |odds| ÷ (|odds| + 100) × 100. E.g. -110 implies 110 ÷ 210 × 100 = 52.4%.

Why do both sides of a bet add up to more than 100%?

Because sportsbook odds include a built-in margin called the vig (or juice/hold). A standard -110/-110 two-way line implies roughly 104.5% combined — the extra 4.5% is the book's edge, not real probability.

How do you remove the vig to find fair probability?

Add up the raw implied probabilities of every outcome in the market, then divide each individual outcome's raw probability by that sum. The results now add up to exactly 100% and represent the market's fair, no-vig probability.

What's a normal sportsbook hold percentage?

A standard -110/-110 two-way line holds about 4.5%. Player props, parlays, teasers and live/in-play markets typically carry a higher hold (sometimes 8–15%+), since they're harder to price and shop around for.

Is this implied probability calculator free?

Yes — free, unlimited and 100% in-browser. No sign-up, no third-party API, nothing uploaded.

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