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Q1 Calculator – First Quartile

Statistics & Probability · Percentiles

Quick answer

If values are 12, 15, 15, 18, 22, 27, 31, the q1 is 15.

First quartile: Position = 0.25 × (n − 1) in the sorted list; interpolate if it falls between two values.

Enter your values

  • 12
  • 15
  • 15
  • 18
  • 22
  • 27
  • 31
7 values

Q1

15

The value a quarter of the way through the sorted data — 25% of values fall below it.

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About the Q1 Calculator – First Quartile

Q1, the first quartile, is the value below which a quarter (25%) of the data falls. Together with the median and Q3 it divides a data set into four equal parts. Enter your values to find it.

For 12, 15, 15, 18, 22, 27 and 31, Q1 is 15.

First quartile

Position = 0.25 × (n − 1) in the sorted list; interpolate if it falls between two values

Things to keep in mind

  • This calculator uses linear interpolation between the closest ranks, the same as Excel's PERCENTILE.INC. Other methods can give slightly different quartiles.
  • Q3 − Q1 is the interquartile range.
  • Quartiles are less affected by extreme values than the mean.
STATISTICS & PROBABILITY GUIDE

A quick guide to Q1

Use it to get an accurate q1 in seconds — free, with no sign-up.

  • Instant results

    See your q1 the moment you enter your numbers.

  • Free, no sign-up

    Every calculator here is free to use, with no account required.

  • Accurate & transparent

    The same standard formula runs on our server for every calculation.

How to Use the Q1 Calculator

1

Enter Values

Provide your values.

2

View Your Results

Get your q1 instantly, calculated on our server.

What is Q1?

This statistics & probability tool works out your q1 instantly, so you don't have to do the math by hand.

“One quick calculation, so you always know your q1 before you decide.”

What Affects Your Q1

Your q1 depends on the values below.

  • Values

    Changing your values changes your q1.

Example Result

Here's what you can expect from a q1 calculation:

Q1
15

Frequently Asked Questions

How to calculate q1?
Fill in values in the Q1 Calculator – First Quartile above and your q1 is calculated instantly. Change any value to see how the result responds.
What does an example q1 calculation look like?
If values are 12, 15, 15, 18, 22, 27, 31, the q1 is 15.
Is this calculator free to use?
Yes — every calculator on this site is completely free, with no sign-up or account required.
How accurate is this calculator?
It uses the standard formula and calculates on our server for every request, so results are precise for the values you enter.
Is my data saved anywhere?
No. Nothing you enter is stored or sent anywhere unless you choose to share a link with your values included.
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Q1

Enter your values

  • 12
  • 15
  • 15
  • 18
  • 22
  • 27
  • 31
7 values

Q1

15

The value a quarter of the way through the sorted data — 25% of values fall below it.

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