Statistics How To

Interquartile Range Calculator

Calculators > Interquartile range calculator

This interquartile range calculator finds the IQR for you, along with the 25th percentile, the 50th percentile (the median) and the 75th percentile. The calculator then subtracts the 75th percentile from the 25th percentile to find the interquartile range using the formula Q3 – Q1 = IQR. Just type your numbers into the text box and click the “Find the interquartile range” button! Read below for more instructions.

Data set:


Results

  • 25th Percentile:
  • 50th Percentile:
  • 75th Percentile:
  • Interquartile Range:


Tip: You don’t have to enter your numbers separated by commas in the text box; you can just type in a list of numbers and the calculator will add the commas for you!

The Interquartile Range Calculator enables you to enter a series of numbers and get the interquartile range without having to solve the interquartile range equation. The interquartile range is the difference between the third quartile and the first quartile in a data set, giving the middle 50%. The interquartile range is a measure of spread; it’s used to build box plots, determine normal distributions and as a way to determine outliers.

The interquartile range is the middle 50% of a data set. Box and whiskers image by Jhguch at en.wikipedia

The interquartile range is the middle 50% of a data set. Box and whiskers image by Jhguch at en.wikipedia

Contents:

Click to skip to the section:

  1. How to use the Interquartile Range Calculator
  2. Quartile Calculator/Quartile Finder

How to use the Interquartile Range Calculator

Example 1:

Watch the video below to learn how to use the calculator or follow the steps below:

Sample question: Find the interquartile range for this set of numbers: 1, 2, 4, 5, 7, 9, 10, 14, 17:

Step 1: Type your numbers into the text box. The commas are optional; you can just separate each number with a space if you like. If you don’t enter commas, the calculator will put the commas in for you.
Step 2: Press the “Find the Interquartile Range!” button.
Step 3: Scroll down to find the solution. The calculator will give you the interquartile range (which for this particular set of data is 9) and it also returns the 1st quartile (25th percentile), 2nd quartile (50th percentile — the median) and the third quartile (75th percentile).

25th Percentile: 3
50th Percentile: 7
75th Percentile: 12
Interquartile Range: 9

Tip: If you wanted to figure out the interquartile range manually, the formula the calculator uses is IQR = Q3 – Q1 =
9.5 – 3 = 6.5

Example 2

Sample Question: Find the interquartile range for the following data set: 12, 13, 15, 18, 19, 22, 88, 89, 90, 91, 92, 93, 95, 98, 99, 101, 101, 103, 105, 106, 107, 108, 109, 200, 201, 201, 203, 204, 215, 216, 217, 222, 223, 224, 225, 227, 229, 230, 232, 245, 246, 250, 258, 270, 271, 271, 272, 273.

Step 1: Type your data into the Data set: box. Separate each number with commas. It may be faster to copy and paste your data if you have a large data set. For this sample question, the data is already separated by commas, so type “12, 13, 15, 18, 19, 22, 88, 89, 90, 91, 92, 93, 95, 98, 99, 101, 101, 103, 105, 106, 107, 108, 109, 200, 201, 201, 203, 204, 215, 216, 217, 222, 223, 224, 225, 227, 229, 230, 232, 245, 246, 250, 258, 270, 271, 271, 272, 273” into the Data Set: box.

Step 2: Click the “Find the Interquartile Range!” button. The interquartile range is displayed at the bottom of the results list, in bold. For the sample data set, the results are:
Results

  • 25th Percentile: 94
  • 50th Percentile: 200.5
  • 75th Percentile: 228

Interquartile Range: 134

Tip: The interquartile range equation is IQR = Q3 – Q1. Therefore, if you need to show your working out (say, for homework), you can substitute the following from the results list into the equation:
75th percentile 200.5 for Q1
25th percentile 228 for Q2
Giving: IQR = Q3 – Q1 = 200.5 – 94 = 134

Quartile Calculator/Quartile Finder

The interquartile range calculator on this site is also a quartile calculator. It not only finds the interquartile range, it finds the first quartile and the third quartile for any set of numerical data.

  1. Type your data into the Data Set box.
  2. quartile finder

    Data entered into the text box.

  3. Click “Find the Interquartile Range.”
  4. Read the results.
      Reading the results from the quartile calculator.

      Reading the results from the quartile calculator.

    1. The 25th percentile is the first quartile.
    2. The 75th percentile is the third quartile.

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Interquartile Range Calculator was last modified: November 13th, 2016 by Stephanie

13 thoughts on “Interquartile Range Calculator

  1. Tasha Terry

    This demonstration was very helpfully for my 11 year old, it was great for him to see it been done ..

  2. l.molnar

    Step 3. of your example 1 is in error. You inadvertantly omitted 17 from your data set when entering the values into the the calculator. The IQR should be 9 not 6.5. ; 50 th percentile: 7 and the 75th: 12

  3. mike

    I’m studying for my GED so it show me this about Outliers it doesn’t make sense the problem they showed and I can’t figure it out. the means how it comes to 5.86 and the 19.14 can you help

    Data set no liers
    3,3,4,4,4,5,5,6,7 means 5.86
    mediam 4
    mode 4
    Data set with an Outlier
    3,3,4,4,4,5,5,6,100 means 19.14
    median 4
    mode 4

  4. Patrick Carney

    Does this calculator work with percentages? That is, I have a range of participation rates that I need to create percentiles with. Would that affect how I use this? Thanks!

  5. Andale

    If you want to calculate the IQR for a list of percents, the calculator will work, but you’ll need to remove the % signs.

  6. Iris

    Describe the data. Include a discussion of the range, where the data are concentrated or spread out, whether there are any outliers, and what is typical about the data set as a whole?

    4,10,3,6,11 1/2,4 1/2,9,12 1/2,3,2,2 1/2,4,11,4 1/2,7 1/2,11 what number is a outlier?

  7. Andale

    Hi, Jeff. The book is a shortened version of the site. Most people like the format, but if it doesn’t work for you let me know! If you purchased it here, I can also send you a refund. Regards, Stephanie.

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