Which quartile method does the calculator use?

The exclusive method (as on TI-83/84 calculators): the median is excluded from both halves before Q1 and Q3 are found.

What counts as an outlier?

Any value below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR.

When should I use a stem-and-leaf plot instead of a histogram?

For smaller datasets where you want to see each value as well as the overall shape. Histograms scale better to large datasets.

Why does Excel give a different Q1 and Q3?

Excel’s QUARTILE.INC uses an inclusive method that interpolates differently, so results can differ slightly for the same data.

Statistics Calculators

Statistics calculators for describing a dataset: find the five-number summary, IQR, and outliers, or build a stem-and-leaf plot to see the shape of your data.

5 Number Summary Calculator

Calculate the five-number summary (min, Q1, median, Q3, max) of a dataset, including IQR and outliers.

statistics quartile median

Stem and Leaf Plot Calculator

Generate an accurate stem-and-leaf plot from any dataset. Supports ones, tens, and hundreds stem units with sorted data, key, range, and step-by-step construction.

stem and leaf stemplot statistics

Summarising a dataset in five numbers

The five-number summary (minimum, first quartile, median, third quartile, maximum) describes where data sits and how spread out it is, without assuming any particular distribution. It is the basis of the box plot and is robust to extreme values in a way the mean and standard deviation are not.

The 5 Number Summary Calculator also reports the interquartile range (IQR = Q3 − Q1) and flags outliers using the 1.5 × IQR rule. It finds quartiles with the exclusive method used by TI-83/84 calculators and many introductory textbooks, which leaves the median out of both halves.

Seeing the shape with a stem-and-leaf plot

A stem-and-leaf plot sorts data while keeping every individual value visible. Each number is split into a stem (the leading digits) and a leaf (the last digit), so the plot reads like a sideways histogram where you can still recover the original data.

The Stem and Leaf Plot Calculator supports ones, tens, and hundreds as the stem unit, sorts leaves within each stem, and always prints a key so the magnitude is clear. It is useful for spotting clusters, gaps, and skew in small to medium datasets.

Key formulas

Interquartile range: IQR = Q3 − Q1
Lower outlier fence: Q1 − 1.5 × IQR
Upper outlier fence: Q3 + 1.5 × IQR

Getting accurate results

Different textbooks and software compute quartiles differently. If your answer differs slightly from Excel, the quartile method is the likely reason.
An outlier flag is a prompt to check the data, not proof the value is wrong.
Choose a stem unit that gives roughly 5–15 stems; too few hides the shape and too many spreads it out.
Separate values with commas or new lines, which both calculators accept.

Frequently asked questions

Which quartile method does the calculator use?: The exclusive method (as on TI-83/84 calculators): the median is excluded from both halves before Q1 and Q3 are found.
What counts as an outlier?: Any value below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR.
When should I use a stem-and-leaf plot instead of a histogram?: For smaller datasets where you want to see each value as well as the overall shape. Histograms scale better to large datasets.
Why does Excel give a different Q1 and Q3?: Excel’s QUARTILE.INC uses an inclusive method that interpolates differently, so results can differ slightly for the same data.

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