Risk Ratio, Odds Ratio and Risk Difference With Intervals
Risk ratio, odds ratio and risk difference with 95% intervals from event counts in two groups.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Group 1 (treated or exposed)
- 141
- Group 1: total
- 561
- Group 2 (comparison)
- 928
- Group 2: total
- 14453
Result: Risk ratio 3.91 (95% CI 3.35 to 4.57); odds ratio 4.89 (95% CI 4.00 to 5.99); risk difference 18.7 percentage points (95% CI 15.1 to 22.3).
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Group 1 (treated or exposed): events
- Group 1: total
- Group 2 (comparison): events
- Group 2: total
How this is calculated
Citation
Deeks JJ, Higgins JPT. Statistical algorithms in Review Manager (Cochrane, May 2022): standard errors of ln RR, ln OR and the risk difference. Bland JM, Altman DG. The odds ratio. BMJ 2000;320:1468. Altman DG. BMJ 1998;317:1309-1312 (NNT interval). Read the sources: Statistical algorithms in RevMan ↗, Bland and Altman 2000 ↗, Altman 1998 (NNT interval) ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.