Interquartile Range (IQR) Calculator

The IQR is the spread of the middle half of the data: the third quartile minus the first quartile (Q3 minus Q1). Because it ignores the highest and lowest values, it is resistant to extreme numbers and describes the typical spread.

Linear interpolation between the two closest ranks, the same rule as Excel PERCENTILE.INC and NumPy's default. The position of a quartile is (n minus 1) times the percentile on a zero based index, then blended. Tools that use a different rule can report slightly different Q1 and Q3 values.

By Tukey's fences. The lower fence is Q1 minus 1.5 times the IQR and the upper fence is Q3 plus 1.5 times the IQR. Any value below the lower fence or above the upper fence is listed as an outlier.

The full range depends on the two most extreme values, so a single outlier can inflate it wildly. The IQR trims both tails and reflects where the bulk of the data actually sits, which makes it a steadier measure of spread.

No. The calculator sorts your values before computing anything, so you can paste them in any order, including straight from a spreadsheet column or a messy log.

Use commas, spaces, new lines, or any mix of them. For example 1, 2 3\n4 all parse to the same four numbers. Negative numbers and decimals such as -2.5 are supported.

One value works, though quartiles are only meaningful with several. Fences can be negative when the data includes small or negative numbers, which is expected: a negative lower fence just means no low outliers are possible.

Most differences come from the quartile method. Some tools exclude the median when splitting the data (Tukey's hinges or the exclusive method) and produce different quartiles for the same set. This tool uses the inclusive interpolation method described above.

Yes. Every calculation happens locally in your browser and nothing is uploaded, so you can paste sensitive measurements without them leaving your device.