What is implied probability?

Implied probability is the win percentage that a set of odds represents. For example, decimal odds of 2.00 imply a 50% chance of winning — at exactly that probability, the bet breaks even over time.

How do you convert decimal odds to implied probability?

Divide 1 by the decimal odds, then multiply by 100. For odds of 1.80: (1 / 1.80) × 100 = 55.56%.

How do you convert fractional odds to implied probability?

Use the formula: denominator / (numerator + denominator) × 100. For 5/2 odds: 2 / (5 + 2) × 100 = 28.57%.

How do positive and negative American odds differ?

Positive odds (e.g. +150) show how much profit a $100 bet returns. Negative odds (e.g. -200) show how much you must bet to win $100. Both can be converted to implied probability using standard formulas.

Why do the implied probabilities across outcomes add up to more than 100%?

Bookmakers build in a margin (the "vig" or "juice") so that probabilities across all outcomes exceed 100%. The excess percentage is the bookmaker's edge.

Implied Probability Odds Calculator

Name: Implied Probability Odds Calculator
Availability: InStock
Author: Nham Vu

Enter decimal, fractional, or American odds and get the implied probability percentage instantly.

Odds Format

Decimal Odds (e.g. 2.50)

Quick Examples

Enter odds on the left to calculate

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Summary

Enter decimal, fractional, or American odds and get the implied probability percentage instantly.

How it works

Select the odds format: Decimal, Fractional, or American (moneyline).
Enter the odds value in the input field.
The implied probability percentage appears instantly.
Use the reverse tab to find odds from a known probability.
Results update in real time as you type.

Use cases

Evaluate whether a bet offers value by comparing implied probability to your own estimate.
Convert between odds formats when switching between bookmakers.
Check the break-even win rate required to profit on a series of wagers.
Understand market-implied probability on binary outcomes (elections, sports, finance).
Convert odds for arbitrage calculations across different formats.
Teach probability concepts using real-world odds examples.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu