Quartile Calculator

Use this quartile calculator to summarize any list of numbers with clear quartiles.

It now computes quartiles correctly for all dataset sizes and also shows the interquartile range.

Results are quick and precise, with a unique focus on clarity.

What It Does

This tool splits your data using standard percentiles and simple math.

• Count: Total number of valid values in your list.
• Sorted data: Your numbers arranged from smallest to largest.
• Minimum: The smallest value in the list.
• Q1: The first quartile at the 25th percentile.
• Median: The second quartile at the 50th percentile.
• Q3: The third quartile at the 75th percentile.
• Maximum: The largest value in the list.
• IQR: The interquartile range, which is Q3 minus Q1.

Use IQR to spot spread and possible outliers with a simple rule.

Values below Q1 minus 1.5 times IQR may be outliers, and values above Q3 plus 1.5 times IQR may be outliers.

How It Works

Enter numbers separated by commas, spaces, or line breaks.

The calculator cleans and sorts your data, then applies a percentile method.

It uses linear interpolation for percentiles and blends neighbors when needed.

Non integer results display with two decimal places to keep results readable.

You need at least three numbers for quartiles, and the tool checks for valid values.

Decimals work well, and negative numbers work too.

Use a dot for decimal points to avoid parsing issues.

Input field: Enter numbers in one box using commas, spaces, or new lines.

Action buttons: Calculate Quartiles runs the math, and Clear All resets the form.

Shortcut: Press Control and Enter to calculate without clicking.

Step-by-Step Instructions

1. Enter your numbers in the text box, and separate them with commas, spaces, or new lines.

2. Click Calculate Quartiles, or press Control and Enter to run the calculation.

3. Review the results on the page, then click Clear All to start a fresh run.

How to read the output:

• Check Count first to confirm all values were read.
• Scan Sorted data to see gaps and clusters in your list.
• Minimum and Maximum show the range your data covers.
• Q1, Median, and Q3 show where quarter marks fall across the list.
• IQR shows spread across the middle half of your data.

Limitations and notes:

• Use at least three numbers for quartiles to compute.
• Use only numbers, since text entries will trigger an error.
• Decimals are allowed, and the tool rounds to two decimals for display.
• Large or small values work fine, and duplicates are handled as expected.
• The method uses percentiles with linear interpolation across ranks.

Quick example:

Data: 7, 3, 5, 9, 1

Sorted data: 1, 3, 5, 7, 9

Minimum: 1

Q1: 3

Median: 5

Q3: 7

Maximum: 9

IQR: 4

Common use cases:

• Grade analysis for a class or a test group.
• Sales spread across stores or months.
• Response times for support tickets.
• Lab readings for quality checks.
• Order values for weekly reports.

The quartile calculator keeps your workflow simple and your stats clear.

Type, click, and read your results with confidence.