---
title: "Quartile and Interquartile Range Calculator | Numequo"
description: "Sort a dataset, calculate its quartiles and IQR, and explore its distribution on a visual scale. Free, fast and easy to use."
canonical: "https://www.numequo.com/math/descriptive-statistics/quartile-interquartile-range-calculator/"
locale: "en"
---
[Numequo](https://www.numequo.com/) › [Math](https://www.numequo.com/math/) › [Descriptive statistics](https://www.numequo.com/math/descriptive-statistics/)

# Quartile and Interquartile Range Calculator

Paste your values separated by spaces, semicolons or line breaks to reveal the five-number summary and possible outliers.

## Input data

- **Dataset** - type: text; default: 4; 7; 7; 9; 12; 15; 18; 21; 24; Example: 4; 7; 7; 9; 12; 15

## How it works

The data are sorted first. Q2 is the median; Q1 and Q3 are the medians of the lower and upper halves. IQR = Q3 − Q1.

## Quick examples

- **Balanced series** - Dataset: 4; 7; 7; 9; 12; 15; 18; 21; 24
- **Series with an outlier** - Dataset: 10; 11; 12; 12; 13; 14; 15; 40
- **Decimal values** - Dataset: 1.5; 2.2; 2.8; 3.1; 4.6; 5.4

## Understanding your result

The middle 50% of the data lies between Q1 and Q3. A small IQR indicates concentrated central values; a large IQR indicates greater dispersion.

Last verified: 29 September 2026 (2026-09-29)

## Frequently asked questions

### What does the interquartile range measure?

It measures the spread of the middle 50% of a dataset and is less sensitive to extreme values than the full range.

### How are quartiles calculated here?

This calculator uses the median-of-halves method: when the dataset size is odd, the overall median is excluded from both halves.

### Why can another calculator return different quartiles?

Several accepted quartile conventions exist. Spreadsheet software may use interpolated percentiles, which can differ from the median-of-halves method.

### How are possible outliers identified?

Values below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR are flagged as possible outliers.

## Related calculators

- [Weighted Average Calculator](https://www.numequo.com/math/descriptive-statistics/weighted-average-calculator/) - Calculate a weighted average and understand the contribution of every value and coefficient.
- [Rounding Calculator](https://www.numequo.com/math/numbers-notation/rounding-calculator/) - Round a number to a chosen decimal place and see which digit determines the result.
- [Significant Figures Calculator](https://www.numequo.com/math/numbers-notation/significant-figures-calculator/) - Round a value to the requested number of significant figures and identify its first significant digit.
- [Percentage Calculator](https://www.numequo.com/math/percentages/percentage-calculator/) - Find any percentage of a number instantly.
- [Percentage Change Calculator](https://www.numequo.com/math/percentages/percentage-change-calculator/) - Measure the increase or decrease between two values.
- [Rule of Three Calculator](https://www.numequo.com/math/proportions-ratios/rule-of-three-calculator/) - Solve a direct proportion from three known values and see every cross-multiplication step.

## Structured data

```json
{
  "@context": "https://schema.org",
  "@graph": [
    {
      "@type": "WebPage",
      "@id": "https://www.numequo.com/math/descriptive-statistics/quartile-interquartile-range-calculator/#page",
      "name": "Quartile and Interquartile Range Calculator | Numequo",
      "description": "Sort a dataset, calculate its quartiles and IQR, and explore its distribution on a visual scale. Free, fast and easy to use.",
      "url": "https://www.numequo.com/math/descriptive-statistics/quartile-interquartile-range-calculator/",
      "inLanguage": "en",
      "isPartOf": {
        "@type": "WebSite",
        "name": "Numequo",
        "url": "https://www.numequo.com/"
      }
    },
    {
      "@type": "BreadcrumbList",
      "itemListElement": [
        {
          "@type": "ListItem",
          "position": 1,
          "name": "Numequo",
          "item": "https://www.numequo.com/"
        },
        {
          "@type": "ListItem",
          "position": 2,
          "name": "Math",
          "item": "https://www.numequo.com/math/"
        },
        {
          "@type": "ListItem",
          "position": 3,
          "name": "Descriptive statistics",
          "item": "https://www.numequo.com/math/descriptive-statistics/"
        },
        {
          "@type": "ListItem",
          "position": 4,
          "name": "Quartile and Interquartile Range Calculator",
          "item": "https://www.numequo.com/math/descriptive-statistics/quartile-interquartile-range-calculator/"
        }
      ]
    },
    {
      "@type": "WebApplication",
      "name": "Quartile and Interquartile Range Calculator",
      "description": "Sort a dataset, calculate its quartiles and IQR, and explore its distribution on a visual scale.",
      "url": "https://www.numequo.com/math/descriptive-statistics/quartile-interquartile-range-calculator/",
      "applicationCategory": "UtilitiesApplication",
      "operatingSystem": "Any",
      "offers": {
        "@type": "Offer",
        "price": "0",
        "priceCurrency": "EUR"
      }
    },
    {
      "@type": "FAQPage",
      "mainEntity": [
        {
          "@type": "Question",
          "name": "What does the interquartile range measure?",
          "acceptedAnswer": {
            "@type": "Answer",
            "text": "It measures the spread of the middle 50% of a dataset and is less sensitive to extreme values than the full range."
          }
        },
        {
          "@type": "Question",
          "name": "How are quartiles calculated here?",
          "acceptedAnswer": {
            "@type": "Answer",
            "text": "This calculator uses the median-of-halves method: when the dataset size is odd, the overall median is excluded from both halves."
          }
        },
        {
          "@type": "Question",
          "name": "Why can another calculator return different quartiles?",
          "acceptedAnswer": {
            "@type": "Answer",
            "text": "Several accepted quartile conventions exist. Spreadsheet software may use interpolated percentiles, which can differ from the median-of-halves method."
          }
        },
        {
          "@type": "Question",
          "name": "How are possible outliers identified?",
          "acceptedAnswer": {
            "@type": "Answer",
            "text": "Values below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR are flagged as possible outliers."
          }
        }
      ]
    }
  ]
}
```