Quartile Calculator

Quartiles split sorted data into four equal parts. Q1 has a quarter of the values below it, Q2 is the median and Q3 has three quarters below it.

Separate numbers with commas or spaces.
Results update as you type.

Q1 · Q2 (median) · Q3

15 · 40 · 43

Five-number summary
6, 15, 40, 43, 49min, Q1, median, Q3, max
Interquartile range (Q3 − Q1)
28
Quartile deviation
14(Q3 − Q1) ÷ 2
Count
11

About this calculator

There are several methods in use. The default follows the (n + 1) ÷ 4 rule taught in Indian textbooks; switch to match Excel or Google Sheets.

How to use it

  1. Enter the numbers.
  2. Choose the method.
  3. Read Q1, Q2, Q3 and the summary.

The formula

Q1 = ((n + 1) ÷ 4)th value; Q3 = (3(n + 1) ÷ 4)th value
n
number of values, after sorting

Worked example

6, 7, 15, 36, 39, 40, 41, 42, 43, 47, 49

  1. n = 11, so Q1 is the 3rd value (15) and Q3 the 9th value (43).
  2. The median is the 6th value, 40.

What the result means

The five-number summary (minimum, Q1, median, Q3, maximum) is what a box plot draws.

Assumptions

  • At least 3 numbers.

Limitations

  • Methods give different results for small data sets; the difference shrinks as data grow.

Frequently asked questions

Why does Excel give a different Q1?

QUARTILE.INC uses position (n − 1) × 0.25 + 1, while textbooks use (n + 1) ÷ 4.

What is quartile deviation?

Half the interquartile range: (Q3 − Q1) ÷ 2.

Is Q2 the median?

Yes.

Last reviewed on 6 October 2026. Found a mistake? Tell us.