How to use the Quartile Calculator
Paste your numbers separated by commas, spaces or new lines. You get Q1, the median and Q3 for the sorted data.
What quartiles show
Quartiles cut sorted data into four groups with the same number of values. A quarter of the data sits below Q1, half below the median and three quarters below Q3. Together with the minimum and maximum, they make the five number summary behind every box plot.
Why your software may disagree
With few values, there is no single agreed way to split the halves. Some methods include the median in each half, others do not, and spreadsheets use interpolation. The median is the same in every method, and the differences shrink as your data set grows, so do not worry about small gaps between tools.
How it works
Sort the data; Q2 is the median, Q1 is the median of the lower half and Q3 the median of the upper half
Examples
- 2, 4, 6, 8, 10
Q1: 4 Median: 6 Q3: 8
- 12, 15, 21, 22, 30, 34, 41, 55
Q1: 19.5 Median: 26 Q3: 35.75
- Exam scores
Q1: 68 Median: 74 Q3: 85
Limitations and assumptions
Several quartile methods exist, so on small data sets Q1 and Q3 can differ slightly from Excel or other software.
Frequently asked questions
What are quartiles?
Q1 is the median of the lower half, Q2 is the median and Q3 is the median of the upper half.
How do I find the interquartile range?
Subtract Q1 from Q3, or use the IQR calculator.
Do methods differ?
Yes, textbooks and software use slightly different conventions, so small differences are normal.
What are quartiles used for?
Box plots and spotting outliers.