Quartiles Calculator
Compute Q1, Q2, Q3 from a dataset using the percentile interpolation method.
Inputs
Q1 (25th percentile)
20.2500
Q2 (Median)
37.5000
Q3 (75th percentile)
39.7500
Step by step
Values used
Data (comma separated) = 7, 15, 36, 39, 40, 41
Formula applied
Qk at position p = (k/4)(n−1), interpolate between floor(p) and ceil(p)
Q1 (25th percentile)
= 20.2500
Q2 (Median)
= 37.5000
Q3 (75th percentile)
= 39.7500
How it works
Quartiles divide an ordered dataset into four equal parts. Q1 is the 25th percentile, Q2 the 50th (median), and Q3 the 75th percentile. This calculator uses the linear interpolation method (R-7).
Formula
Qk at position p = (k/4)(n−1), interpolate between floor(p) and ceil(p)
- k
- Quartile number (1–3)
- n
- Sample size
- p
- Position index
Frequently Asked Questions
What method is used to compute quartiles?
This calculator uses the inclusive (R-7) percentile method with linear interpolation, which matches Excel's QUARTILE.INC function.
How do quartiles relate to percentiles?
Q1 = 25th percentile, Q2 = 50th percentile (the median), and Q3 = 75th percentile. They split the sorted data into four equal-sized groups.