Everyday Tools

Interquartile Range Calculator

Calculate Q1, Q3, and interquartile range from a list of numbers.

Updated April 14, 2026
Free online tool
Planning and research use

Why this page exists

Spread is easier to understand when a number list is turned into quartiles and an interquartile range instead of being judged by eye. This calculator helps visitors estimate Q1, Q3, and interquartile range from comma-separated values using one consistent quartile method.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Interquartile range calculator

Estimate Q1, Q3, and interquartile range from a comma-separated list of numbers.

Result

11.5000

Estimated first quartile, third quartile, and interquartile range from the numbers entered using the median-of-halves quartile method.

Interquartile range11.5000

Q18.0000

Q319.5000

Number count used8

Using the median-of-halves method on 8 values gives a Q1 near 8.0000 and a Q3 near 19.5000.
The middle value of the full sorted list is about 11.5000, and the interquartile range between Q1 and Q3 is about 11.5000.
Different software can use different quartile conventions, so match the same quartile method whenever you compare results.

This calculator uses the median-of-halves quartile method, excluding the overall median when the full list has an odd number of values. Different software packages can use different quartile conventions.

Planning note

Last updated April 14, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter numbers separated by commas.

The calculator sorts the valid values from low to high.

It uses the median-of-halves method to estimate Q1, Q3, and interquartile range.

Understanding your result

Browse more everyday tools

Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Measure spread without focusing on extremes

Interquartile range can help show how wide the middle half of the data is without leaning too heavily on the smallest and largest values.

Turn a raw list into quartiles quickly

Sorting and splitting the list automatically can save time when you only want the quartile summary.

Use it with other descriptive-statistics tools

IQR often makes more sense when viewed beside median, percentile, and standard-deviation measures.

FAQ

Common questions

How does this calculator estimate quartiles?

It sorts the values, splits the ordered list into lower and upper halves, and uses the median of each half to estimate Q1 and Q3.

What quartile method does this use?

It uses the median-of-halves method, excluding the overall median when the full list has an odd number of values.

Why can quartiles differ across tools?

Different calculators and software packages can use different quartile definitions, so matching the same convention is important when comparing results.

Related tools

Keep comparing

Use these related tools to compare nearby scenarios, check a second estimate, or keep narrowing down the right decision.

Everyday ToolsUpdated April 12, 2026