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Formula verified · Deterministic calculation

Interquartile Range Calculator

Enter a numeric dataset to calculate Q1, Q3 and the interquartile range for the middle 50% of the ordered observations.

Interquartile range1.5
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Result methodology

Deterministic calculation using the displayed formula and supplied inputs.

Solution steps
  1. Q1 = 1.75
  2. Q3 = 3.25
  3. IQR = Q3 − Q1 = 1.5

How this calculator works

IQR=Q3−Q1.

Formula

IQR=Q3−Q1

Measures the middle 50% spread of ordered data.

Worked example

Middle 50 percent spread is a verified test case used by the calculation engine.

Assumptions and limitations

  • The dataset contains numeric observations.
  • Q1 and Q3 use the calculator's linear-position convention.
  • IQR describes the middle 50% spread.

Methodology & sources

This calculator uses deterministic, versioned calculation logic. The formula and verified examples above are part of the calculation definition used by CalcuMint.

  • CalcuMint deterministic statistics engine

Frequently asked questions

What does IQR measure?

IQR measures the distance between the first and third quartiles, representing the middle 50% spread.

Is IQR affected by extreme values?

It is generally less sensitive to extreme observations than the full range.

Related calculators

Quartile CalculatorCalculate Q1, Q2 or Q3 for a numeric dataset.Percentile CalculatorCalculate a percentile using linear interpolation of ordered data.Standard Deviation CalculatorCalculate population or sample standard deviation and variance.