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Quartile Calculator

Instantly calculate the 5-number summary (Min, Q1, Median, Q3, Max), Interquartile Range (IQR), and detect statistical outliers.

Enter Dataset

Descriptive Stats

You can paste raw data directly from Excel or a spreadsheet.

The "Exclusive" method excludes the median when splitting the dataset in half, which is the standard taught in most schools.

Results

Enter your dataset and hit calculate to view the 5-number summary.

Understanding Quartiles & IQR

In descriptive statistics, quartiles are values that divide a rank-ordered dataset into four equal parts. They form the basis of the "five-number summary" and are frequently used to build box-and-whisker plots. Our Quartile Calculator handles the sorting and mathematical splitting for you instantly.

If you are analyzing the dispersion of your data alongside quartiles, you may also find our Sample Variance Calculator highly useful.

The 5-Number Summary

When you input your data, the calculator first sorts the numbers from lowest to highest. It then extracts these five key data points:

  • Minimum: The lowest number in the dataset.
  • First Quartile (Q1): The median of the lower half of the data (the 25th percentile).
  • Median (Q2): The exact middle value of the dataset (the 50th percentile).
  • Third Quartile (Q3): The median of the upper half of the data (the 75th percentile).
  • Maximum: The highest number in the dataset.

Finding Outliers with the IQR

The Interquartile Range (IQR) represents the middle 50% of your data and is calculated simply as Q3 - Q1.

The IQR is the standard mathematical tool used to identify statistical outliers. A data point is considered an outlier if it falls outside the "inner fences":

  • Lower Fence = Q1 - (1.5 × IQR)
  • Upper Fence = Q3 + (1.5 × IQR)

Any value smaller than the Lower Fence or larger than the Upper Fence is flagged in red by the calculator.