Quartile Calculator
Find Q1 (first quartile), Q2 (median), and Q3 (third quartile) from any dataset. Compare different quartile methods and see step-by-step solutions.
🧮 Calculate Now
📖 How to Use
Step 1: Enter your numbers separated by commas or spaces. Click "Example" for a demo dataset.
Step 2: Click "Calculate" for instant results with box plot and interpretation.
Step 3: Use "Copy" or "CSV" to export results. Click "Recalculate" to try new data.
What Are Quartiles?
Quartiles divide a sorted dataset into four equal parts. Q1 (first quartile) is the 25th percentile — 25% of values fall below it. Q2 is the median (50th percentile). Q3 (third quartile) is the 75th percentile. Together they form the basis of the five-number summary and box plots.
Quartile Calculation Methods
Different software and textbooks use different methods to calculate quartiles. The most common are: Exclusive (median of halves, excluding the overall median for odd datasets), Inclusive (median of halves, including the overall median), and Interpolation (linear interpolation, used by Excel QUARTILE.INC). Use the selector above to compare methods.
How to Find Q1
Sort your data. Find the median position. Q1 is the median of all values below the overall median position. For even datasets, split the data into two equal halves. For odd datasets, whether to include or exclude the median depends on your chosen method.
How to Find Q3
Q3 is the median of all values above the overall median position. The same method-dependent rules about including or excluding the median apply. Q3 minus Q1 gives the interquartile range (IQR).
❓ Frequently Asked Questions
Why do different calculators give different Q1/Q3?
There are multiple valid methods for computing quartiles (exclusive, inclusive, interpolation). Different software uses different methods. Use the method selector above to match your textbook.
What is the difference between Q1 and Q3?
Q1 marks the boundary below which 25% of data falls. Q3 marks the boundary below which 75% falls. The gap Q3−Q1 is the IQR.
🔗 Related Calculators
📊 5 Number Summary
Min, Q1, Median, Q3, Max
📈 Statistics (All-in-One)
Complete descriptive statistics
🔢 Quartile Calculator
Find Q1, Q2, Q3
📏 IQR Calculator
Interquartile range & fences
🎯 Outlier Detection
Find outliers with IQR method
📦 Box Plot
Visual box-and-whisker diagram
➗ Mean Calculator
Arithmetic average
📐 Standard Deviation
Sample & population SD