Interquartile Range Calculator
IQR, quartiles and outlier fences.
Enter your values
Enter the data values you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Interquartile range
- 19.75
- Q1
- 19
- Median (Q2)
- 29
- Q3
- 38.75
- Outlier fences
- -10.625 to 68.375
- Outliers found
- 90
Quick answer
The IQR is Q3 minus Q1, covering the middle 50% of the data and resisting the influence of outliers.
IQR = Q3 − Q1
At a glance
| What it does | IQR, quartiles and outlier fences. |
|---|---|
| Category | Statistics |
| Inputs needed | Data values |
| Main output | Interquartile range |
| Formula | IQR = Q3 − Q1 |
| Cost | Free — no sign-up, no download |
How to use the Interquartile Range Calculator
- 1Paste your data separated by commas.
- 2Read the quartiles and IQR.
- 3Check the outlier list against your data.
Inputs explained
- Data values
- Enter the data values you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Data values12, 15, 18, 22, 27, 31, 35, 40, 52, 90
Results
- Interquartile range19.75
- Q119
- Median (Q2)29
- Q338.75
- Outlier fences-10.625 to 68.375
- Outliers found90
Frequently asked questions
Why use IQR instead of range?
It ignores extreme values, so it describes typical spread better.
What is the 1.5 rule?
Values beyond 1.5 IQR from the quartiles are conventionally flagged as outliers.
What do I need to enter into the Interquartile Range Calculator?
Just 1 value: data values. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Interquartile Range Calculator work out the answer?
The IQR is Q3 minus Q1, covering the middle 50% of the data and resisting the influence of outliers. It applies the formula IQR = Q3 − Q1 and shows the working so you can check each step by hand.
Is the Interquartile Range Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.