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 do I 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
Theory — how are outliers detected using the IQR method?
The IQR rule uses a dataset's quartiles and is resistant to single extreme observations, unlike methods based on the mean and standard deviation. The calculator requires at least four numbers and flags as outliers any values beyond Q1 minus 1.5 IQR or Q3 plus 1.5 IQR — the Tukey fences. Such a value is only a candidate for review, not an automatic data error. Before removing it, its origin must be established — it could be a measurement error, a valid rare case, or part of a different population.
Frequently asked questions
Should I remove every outlier?
Why does this differ from a Z-score method?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.