How it works
Find Q1, median, Q3 and interquartile range using inclusive linear interpolation. Other software may use a different quartile convention.
position = (n−1)p; linear interpolation
Worked example
Show example inputs and result
Numbers: 2 4 4 4 5 5 7 9.
- Q1
- 4
- Median
- 4.5
- Q3
- 5.5
- Interquartile range
- 1.5
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy