Upper Fence Calculator
Enter data and choose a multiplier to calculate the upper fence (Q3 + k × IQR) used in boxplots to flag unusually large values.
Default 1.5 for mild outliers; 3.0 for extreme outliers.
Q1: 15.7500
Q3: 29.2500
IQR: 13.5000
Upper fence: 49.5000
Values above fence: 99
How to Use This Calculator
- Input your dataset values.
- Select a multiplier (commonly 1.5).
- Review quartiles, IQR, and the upper fence.
- Investigate points above the fence as potential outliers.
Formula
Q1 = 25th percentile, Q3 = 75th percentile
IQR = Q3 − Q1
Upper fence = Q3 + k × IQR
Full Description
The upper fence extends beyond the third quartile to mark unusually large observations. It aids in boxplot interpretation and data cleaning by spotlighting values that warrant further review.
Frequently Asked Questions
How does this relate to the lower fence?
The lower fence uses Q1 − k × IQR. Together, the fences bracket the central distribution.
Should outliers always be removed?
No. Use domain knowledge to decide whether flagged points are errors or meaningful observations.
Does the method assume normality?
No. Boxplot fences are distribution-agnostic but interpretation depends on context.
Can I apply different k values?
Yes. Increase k to be more lenient or decrease k to flag more values as potential outliers.