Quartile Calculator

Find the five-number summary of a data set — minimum, Q1, median, Q3 and maximum — plus the IQR and outliers for a box plot.

At least 4 values, separated by commas or spaces

Result

Enter values and press Calculate to see the result.

Formula

IQR=Q3−Q1\text{IQR} = Q_3 - Q_1

The spread of the middle half of the data.

x<Q1−1.5 IQR  or  x>Q3+1.5 IQRx < Q_1 - 1.5\,\text{IQR} \ \text{ or } \ x > Q_3 + 1.5\,\text{IQR}

A value outside these fences is an outlier.

How to use this calculator

  1. Enter at least 4 numbers separated by commas, spaces or new lines.
  2. Press Calculate to get the five-number summary, the IQR and any outliers.

Worked example

Eight test scores

Sorted: 2, 4, 4, 5, 6, 7, 8, 30. The median is (5 + 6) ÷ 2 = 5.5.

Lower half 2, 4, 4, 5 gives Q1 = 4; upper half 6, 7, 8, 30 gives Q3 = 7.5.

IQR = 7.5 − 4 = 3.5. The fences are −1.25 and 12.75, so 30 is an outlier.

Frequently asked questions

Why does my spreadsheet give different quartiles?

There are several quartile methods. Sumzo uses the median-of-halves method taught in most schools; spreadsheet functions such as QUARTILE often interpolate instead.

Is the median included in the halves?

No. With an odd number of values the middle one is left out of both halves.