📦Quartile & IQR Calculator
Find Q1, median, Q3, IQR, and outliers from any data set.
Free IQR Calculator
Need the quartiles, interquartile range, and outliers for a data set? Our free IQR calculator finds Q1, the median, Q3, and the IQR instantly, and flags any outliers using the standard 1.5×IQR rule.
Paste in your data, and see the full working — the sorted list, how it's split into halves, and how each quartile is derived from those halves — plus a box-and-whisker diagram that visualizes the five-number summary and highlights any outlying points. This calculator uses the exclusive (Tukey) median-of-halves method — since different tools can define quartiles slightly differently, the method is stated clearly.
Great for exam prep, lab reports, and spotting outliers in a small data set. No sign-up, no downloads, completely free.
About the Quartile & IQR Calculator
Features
Five-number summary
Min, Q1, median, Q3, and max computed instantly.
Stated quartile method
Uses the exclusive/Tukey method explicitly, since methods vary between tools.
Outlier detection
Flags values outside Q1 − 1.5×IQR and Q3 + 1.5×IQR.
Box-and-whisker diagram
Visualizes the summary with outliers plotted separately.
Frequently Asked Questions
What is the interquartile range (IQR)?
The range between the first quartile (Q1) and third quartile (Q3), covering the middle 50% of the data.
How are quartiles calculated?
The data is sorted and split at the median; Q1 is the median of the lower half, and Q3 is the median of the upper half.
How are outliers identified?
Using the standard rule: any value below Q1 − 1.5×IQR or above Q3 + 1.5×IQR is flagged as an outlier.
Why do different calculators sometimes give slightly different quartiles?
There are several accepted methods for computing quartiles; this tool states clearly which method it uses (exclusive/Tukey) so you can compare results consistently.
What does the box-and-whisker plot show?
The minimum, Q1, median, Q3, and maximum, with any outliers plotted separately as individual points.
How much data do I need?
Quartiles can be computed from as few as 4 points, though more data gives a more meaningful summary.
Does it show the calculation steps?
Yes, the sorted data and how it splits into halves for each quartile is shown.
Can I paste data from a spreadsheet?
Yes, comma-, space-, and newline-separated values are all accepted.
Is my data stored?
No, everything runs client-side in your browser.
Is it free?
Yes, completely free with no sign-up or limits.