Free · Probability and statistical models

American Odds Implied Chance

Convert positive or negative American odds into an implied outcome probability.

  • Formula & worked example
  • Private in your browser
  • No signup
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Odds +100 or −100 imply a 50% chance before any bookmaker margin is removed.

Positive odds: p=100/(o+100). Negative odds magnitude: p=o/(o+100).

Worked example

Enter these known values and leave the other values blank.

American odds (moneyline)
100
Implied probability
50 %

Assumptions and limitations

  • Enter the positive magnitude of the American odds and choose the positive or negative sign separately.
  • The odds magnitude must be positive; zero does not define a standard American odds quote.
  • This gives implied odds arithmetic, without estimating a true winning chance or removing a bookmaker margin.

Common questions

What does the result describe?

It describes the probability implied by the quoted odds under their arithmetic convention.

References

Translate the pinned captured helper to direct standalone arithmetic, preserving every input, selector and output dependency. A standard American odds quote has a positive magnitude; its sign is selected separately.

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