Frequently Asked Questions
Everything you need to know about the Quartile & IQR Calculator.
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.