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Statistics

IQR Outlier Fences Calculator

Calculate Tukey’s lower and upper fences from the sample quartiles.

Data stays on this deviceConvention explained below

Data and assumptions

Runs on your device

STATISTICAL RESULT

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter numbers, iqr multiplier.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Lower fence = Q1 − factor × IQR. Upper fence = Q3 + factor × IQR. Quartiles use Type 7 interpolation.

A WORKED EXAMPLE

Using numbers = 2, 4, 6, 8, iqr multiplier = 1.5, the result is -1 to 11. Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

A flagging rule, not proof that a value is erroneous. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.

Common questions

Which inputs does this calculation need?

Calculate Tukey’s lower and upper fences from the sample quartiles. Enter numbers, iqr multiplier. The filled example is editable and is not a saved personal record.

How should I interpret the result?

A flagging rule, not proof that a value is erroneous. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.

Methodology maintained by ClarityKit. How these tools are built and checked.