Percentile & Quartile Calculator

Where it is used

• Teachers: A teacher enters the exam scores for a class to find the 90th percentile and see which mark puts a student in the top ten percent.
• Cafe and shop owners: A cafe owner pastes in customer wait times to see the quartiles and check how long the slowest quarter of customers had to wait.
• HR staff: An HR officer lists team salaries to find the median and the middle range, so pay can be compared fairly across the group.

Percentiles and quartiles

A percentile is the value below which a given percentage of the data falls. The 25th, 50th and 75th percentiles are the quartiles, and the gap between Q1 and Q3 is the interquartile range (IQR), a robust measure of spread.

When should you use it?

Use it whenever you have a list of numbers and want to understand how they are spread out, not just their average. It is handy for exam scores, prices, wait times, ages, salaries, or survey ratings. Percentiles are useful when you want to know where one value sits compared with the rest, such as a student in the top ten percent. Quartiles are useful when you want a quick picture of the low, middle, and high parts of your numbers in one go, without reading every value yourself.

What does the result mean?

The calculator sorts your numbers and reports the quartiles. The first quartile, or 25th percentile, is the point one quarter of your numbers fall below. The second quartile is the median, the middle value. The third quartile, or 75th percentile, is the point three quarters fall below. There is no single good or bad number here, since it all depends on your data. As a rough guide, the median shows a typical value, and the gap between the first and third quartiles shows how spread out the middle half of your numbers is.

Mistakes to avoid

Do not mix different kinds of numbers in one list, like prices and ages, because the answer will be meaningless. Make sure every entry is a real number with no stray letters, currency signs, or text, as these can be skipped or cause errors. Remember that percentiles need enough numbers to be useful, so a handful of values will give only a rough answer. Also, do not confuse the median with the average. They can be quite different when a few very high or very low numbers are present.

How to use this calculator

1. Enter or paste your list of numbers, separating each one with a comma, a space, or the Enter key.
2. Check that only plain numbers appear, with no letters, symbols, or units.
3. Let the calculator sort them and read the quartiles, plus any percentile it shows.
4. Look at the median for the typical value, and the first and third quartiles to see the spread.

Worked example

Say a teacher has nine test scores: 52, 61, 65, 70, 72, 78, 85, 88, and 95. After entering them, the calculator shows the median (second quartile) as 72, the first quartile as around 63, and the third quartile as around 86. This tells the teacher that a typical score is 72, and the middle half of the class scored roughly between 63 and 86.

Frequently asked questions

Related calculators

• Mean, Median and Mode Calculator
• Standard Deviation Calculator
• Z-Score Calculator