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Statistics

Odds Ratio Calculator

2×2 table to odds ratio with a confidence interval.

Enter your values

ⓘ Live results

Results
Odds ratio
2.6667
95% confidence interval
1.417 to 5.02
Significant?
Yes — the interval excludes 1
Log odds ratio
0.9808
Odds in the exposed group
0.6667
Odds in the unexposed group
0.25

Quick answer

The odds ratio is (a·d) ÷ (b·c) from a 2×2 table; a value of 1 means no association, above 1 means higher odds in the exposed group.

OR = (a·d) ÷ (b·c)

How to use the Odds Ratio Calculator

  1. 1Fill in the four cells of your 2×2 table.
  2. 2Read the odds ratio and its confidence interval.
  3. 3If the interval crosses 1, the association is not statistically significant.

Worked example

Using the values the calculator loads with:

Inputs

  • Exposed with the outcome40
  • Exposed without60
  • Unexposed with the outcome20
  • Unexposed without80

Results

  • Odds ratio2.6667
  • 95% confidence interval1.417 to 5.02
  • Significant?Yes — the interval excludes 1
  • Log odds ratio0.9808
  • Odds in the exposed group0.6667
  • Odds in the unexposed group0.25

Frequently asked questions

Odds ratio or relative risk?

Use relative risk for cohort studies where you can measure risk directly. Odds ratios are the only option in case-control designs.

What if a cell is zero?

The formula breaks. Add 0.5 to every cell (the Haldane correction) or use exact methods.

About this calculator

Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.