Interquartile range calculator
Paste at least four numbers. The tool flags values outside Q1 − 1.5 IQR and Q3 + 1.5 IQR.
Sorted data
| Value | Outside fence |
|---|---|
| Fill in the fields above — the result is computed on this page. | |
How to use this page
- Paste the data.
- Check the quartiles and fences.
- Verify flagged observations against their source.
What this page does not do: Quartiles use R7 interpolation. For small or multimodal data sets, the 1.5 IQR rule may need additional judgement.
Further reading
The IQR rule uses quartiles and is resistant to a few extreme observations. Values outside Tukey fences are candidates for review, not automatic errors.
Before removing an observation, investigate where it came from. It may be a measurement error, a valid rare case or evidence of a separate group in the data.
Frequently asked questions
Should I remove every outlier?
No. First determine whether it is an error, a valid rare case or part of another population.
Why does this differ from a Z-score method?
IQR and Z-score rules use different assumptions; IQR does not depend on the mean and standard deviation.
See also
Beta distribution calculator
Calculate beta density, CDF, upper tail and quantile together with its mean and variance.
Chi-square test calculator
Calculate chi-square goodness of fit, independence, or a chi-square critical value.
Continuous uniform distribution calculator
Calculate density, CDF, upper tail, quantile, mean and variance for U(a,b).