Odds Ratio Calculator
Result
Odds Ratio Calculator — free online calculator.
Formula
- Odds Ratio Calculator calculates its result from a — Exposed & Case (TP), b — Exposed & Control (FP), c — Unexposed & Case (FN), d — Unexposed & Control (TN). It uses the formula OR = (a × d) / (b × c) · 2×2 table: [a b / c d]. Change any input to recalculate the result instantly.
- The main inputs are a — Exposed & Case, b — Exposed & Control, c — Unexposed & Case, d — Unexposed & Control. Enter them in the units and format shown in the calculator.
- Keep comparable quantities in compatible units whenever the formula combines or compares them.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Odds Ratio
- a — Exposed & Case: 50 TP
- b — Exposed & Control: 150 FP
- c — Unexposed & Case: 30 FN
- d — Unexposed & Control: 170 TN
With cells a=50, b=150, c=30, d=170, odds ratio=8500/4500≈1.8889; exposed odds≈0.3333, unexposed odds≈0.1765, subjects=400.
Sample result: Calculating…
Frequently asked questions
What does the Odds Ratio calculate?
Odds Ratio Calculator — free online calculator.
Which values should I enter?
Enter a — Exposed & Case, b — Exposed & Control, c — Unexposed & Case, d — Unexposed & Control using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: OR = (a × d) / (b × c) · 2×2 table: [a b / c d].
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.