Central Tendency
Nov 13, 2025
Mean vs Median vs Mode: When Each Wins
Learn decision frameworks for choosing the right measure of central tendency. Includes real-world examples, outlier handling, and PlotNerd workflows.
14 min read
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Free Box Plot Creator & Quartile Calculator The Fastest & Easiest Online Statistical Tool
Support for Tukey, Excel, R, and Python algorithms. 100% client-side computing ensures complete data privacy.
β¨ Advanced Features
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Multi-Series Comparison: Compare multiple groups
side-by-side with grouped box plots
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MAD Outlier Detection: Robust outlier detection using
Median Absolute Deviation
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Notched Box Plots: Visualize median confidence intervals for statistical significance
| Feature | PlotNerd | Excel | GraphPad |
|---|---|---|---|
| Cost | Free | $160/yr | $600/yr |
| Algorithms | 4 (Toggle) | 1 (Hidden) | 1 (Default) |
| Outlier Detection | IQR + MAD | Manual | ROUT |
Updated November 2025 with MAD Outlier Detection
π οΈ Available Tools
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Tukey Hinges Calculator
The textbook-standard method for calculating quartiles. Perfect for homework and manual verification.
Try Calculator β π
Excel Quartile Calculator
Calculate quartiles using Excel's QUARTILE.INC method. Verify your spreadsheet results instantly.
Try Calculator β π
IQR Calculator
Calculate the Interquartile Range (IQR) and detect outliers using the 1.5ΓIQR rule.
Try Calculator β π
5 Number Summary
Get the complete Min, Q1, Median, Q3, Max summary for your dataset in one click.
Try Calculator β π
Percentile Calculator
Calculate any percentile (25th, 50th, 75th, 90th, 95th, 99th) for test scores and benchmarking.
Try Calculator β π
Standard Deviation Calculator
Calculate sample and population standard deviation, variance, and more. Privacy-focused computation.
Try Calculator βπ Quick Start Guide
1
Enter Your Data
2
Calculate Statistics
3
Generate Box Plot
Waiting for data input...
π 100% local computing, data never leaves browser
Supported Data Formats:
- Comma-separated: 1.5, 2.8, 9.1, 16.2
- Space-separated: 1.5 2.8 9.1 16.2
- Newline-separated: one number per line
- Scientific notation: 1.23e-4, 5.67E+8
- Series mode: use "Group Name: value1, value2, value3" per line to compare multiple groups
- Automatically ignores text and special characters
Universal Standard (R, Python, Google Sheets)
Linear interpolation method, default standard for modern data science software
R (type=7) Python NumPy Google Sheets QUARTILE.EXC
Interpolated Values
Medium Complexity
Your calculation results and box plot will appear here instantly
Please enter at least 4 numbers above to start calculating
Calculating...
Calculation Results
Basic Statistics
Data Count: -
Sum: -
Minimum: -
Maximum: -
Range: -
Mean: -
Quartiles
First Quartile (Q1): -
Median (Q2): -
Third Quartile (Q3): -
Interquartile Range (IQR): -
5 Number Summary
[-,-,-,-,-]
[Min, Q1, Median, Q3, Max]
Outliers Detected
The following data points are identified as outliers using the method:
Grouped Series Summary
Enter data to generate box plot
Please enter at least 4 numbers above to start calculating
Box Plot Visualization
This box plot visualizes your data distribution. The box shows the interquartile range (IQR) containing the middle 50% of data. The line inside the box represents the median. Whiskers extend to show the range, and red dots indicate outliers.
Outlier Method: Tukey (1.5ΓIQR)
Box (IQR) / Legend
- Box (IQR)
- Median Line
- Whisker
- Outliers
Combined Summary
Range: -
Median (Q2): -
Outliers Detected: -
Expert Guides & Tutorials
Complete Guide
The Complete Guide to Quartiles: Everything You Need to Know
Master quartiles with this comprehensive 2500-word guide. Learn calculation methods, real-world applications, and expert tips.
Read Guide β
Technical Deep Dive
Quartile Calculation Methods Compared: R vs Python vs Excel
Why do your results differ? We analyze Hyndman-Fan Types 6, 7, and 8 with code examples for developers.
Read Analysis β
Concept Comparison
Percentile vs Quartile: What's the Difference?
Understand the key differences, relationships, and when to use each measure for your data analysis.
Learn More βWhy Choose PlotNerd?
Statistical Precision
Industry-standard Tukey methods, compatible with major statistical software, featuring WolframAlpha cross-verification
Complete Privacy
100% client-side computing ensures your data never leaves your browser, completely local processing, secure and reliable
Lightning Fast
Real-time input parsing, instant result generation, supports large datasets, no server response delays
Intuitive Design
Multiple data format support, intelligent parsing, one-click copy results, designed for students and researchers
Professional Charts
High-quality SVG box plots, outlier detection, supports PNG/SVG export, perfect for academic and business use
Completely Free
No registration required, no usage limits, forever free, open and transparent, continuous improvement and maintenance
Knowledge Center
Learn the Stories Behind Your Quartiles
Explore tutorials and analysis explainers written by the PlotNerd team. Each article pairs hands-on walkthroughs with direct links back to the calculator.
Visualization Guide
Sep 12, 2025
How to Read a Box Plot: A Simple Guide
Decode every element of box-and-whisker charts, follow a classroom case study, and learn how PlotNerd flags outliers instantly.
11 min read
Read Article
Algorithm Deep Dive
Sep 19, 2025
Tukey's Hinges vs. R-7 Quantiles: How to Pick the Right Quartile Method
See where the two most common quartile algorithms diverge, walk through real datasets, and standardize your reporting workflow with PlotNerd toggles.
13 min read
Read Article
Frequently Asked Questions
Statistical concepts explained in plain language
Mathematical Formulas
View the standard mathematical formulas behind the calculations
Quartile Calculation (Method 2)
First Quartile (Q1):
Median (Q2):
Third Quartile (Q3):
Interquartile Range & Outlier Detection
Interquartile Range (IQR):
Outlier Boundaries:
Algorithm Explanation
PlotNerd uses the statistically standard "Method 2 (Median Quartile Method)" for quartile calculations, consistent with major statistical software (such as R, SPSS). All calculation results are verified against authoritative platforms to ensure accuracy.
Start Your Statistical Analysis Journey
No software download needed, no account registration required, use the professional quartile calculator instantly