Built and fact-checked by the DocNectar team — see our editorial standards
Key Features
Instant Calculation
Get accurate results in real time with our optimized algorithm.
Mobile Friendly
Fully responsive design. Works on all devices & screen sizes.
Privacy Focused
Your data stays on your device. We don't store any inputs.
100% Free
No hidden costs. This tool is completely free forever.
Quartiles divide a sorted dataset into four equal parts, and the gap between the first and third quartile — the interquartile range — is one of the most reliable ways to spot outliers.
This calculator finds Q1, the median, Q3, the IQR, and the standard outlier bounds for any dataset.
How it works
Enter a list of numbers. The calculator sorts them, finds the overall median, splits the data into lower and upper halves (excluding the median itself when the count is odd), and takes the median of each half as Q1 and Q3.
- Enter numbers (comma or space separated).
- Click Calculate to see your results.
Examples
2, 4, 4, 5, 7, 9, 12, 15
This 8-value dataset has Q1 = 4, median = 6, Q3 = 10.5, and an IQR of 6.5 — with outlier bounds from -5.75 to 20.25, meaning none of these values are outliers.
Who should use it
- Checking statistics coursework involving quartiles and the interquartile range.
- Screening a dataset for potential outliers before further analysis.
Industry applications
- Statistics education
- Data analysis and quality control
Advantages
- Reports Q1, median, Q3, IQR, and outlier bounds in a single calculation.
- Automatically lists which values (if any) fall outside the outlier bounds.
Limitations
- Uses one specific quartile method (exclusive median) — results may differ slightly from tools using an inclusive or interpolation-based method.
Common mistakes to avoid
- Expecting quartile values to exactly match a different tool that uses a different quartile method.
- Treating every value outside the outlier bounds as automatically wrong or invalid — the 1.5×IQR rule is a statistical guideline, not a certainty.
Best practices
- Report which quartile method you used when sharing results, since different methods can produce slightly different Q1/Q3 values.
Tips
- The interquartile range is a more robust measure of spread than the full range, since it isn't affected by extreme outlier values the way min/max are.