Free odds calculators
Two calculators for the first steps of any market-implied analysis. Each shows its formula, so the result can be checked by hand.
Reviewed
Calculators
Implied probability calculator
Enter American or decimal odds and get the break-even probability the price implies, with the formula used and a worked example.
No-vig odds calculator
Enter both sides of a two-way market and get normalized no-vig probabilities and decimal odds, along with the displayed overround.
What these calculators do and do not do
Both calculators work on one market at a time. They describe what a price implies; they do not estimate the true probability of an event, and they do not say whether a price is worth taking. Removing the vig proportionally is an assumption about how the margin is spread across outcomes, and the guide to removing vig explains when other methods give different answers.
A single market is also only part of a game. SimTheGame reads every priced market for a matchup together and reconciles them into 10,000 complete game scripts, so the score, the total, and each player's line come from the same simulated games. See today's simulated board for that applied to real games, or read how implied probability works for the arithmetic behind the first calculator.
Reproduce the numbers yourself
The formulas are short enough to check by hand. For negative American odds A, implied probability is |A| / (|A| + 100); for positive American odds it is 100 / (A + 100); for decimal odds D it is 1 / D. To remove the vig from two sides, divide each raw probability by their sum. If a result on this site does not match your own calculation, report it through the corrections process.