Percentile Calculator for Your Data
A [percentile](/percentile-height-weight-baby-who) shows what percentage of data is less than or equal to a given value. If you're at the 80th percentile, you rank higher than 80% of the dataset. This calculator determines the percentile of any value within your data and includes quartiles Q1, Q2, and Q3.
When to use this calculator
- Determine what percentile an exam score falls in.
- Evaluate a measurement against a reference group.
- Calculate quartiles of a dataset.
- Solve descriptive statistics problems.
- Interpret results from standardized tests.
Real-world example: Exam score
- Data: Class scores = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100], your score = 75.
- Calculation: 7 values are less than or equal to 75 (all up to 70), plus interpolation.
- Percentile: ~70. You rank higher than 70% of the class.
- Quartile: Q3 (falls between the 50th and 75th percentiles).
How it works
1 min readWhat is a percentile?
A percentile indicates what percentage of a distribution is less than or equal to a given value. If your height falls at the 80th percentile, you're taller than 80% of the sample. It's a relative ranking measure, widely used in healthcare, education (standardized test scores), psychometrics, and descriptive statistics.
Percentiles and quartiles at a glance
| Percentile | Quartile | Meaning |
|---|---|---|
| P25 | Q1 | 25% below, 75% above |
| P50 | Q2 (median) | Exact midpoint |
| P75 | Q3 | 75% below, 25% above |
| P90 | — | Top 10% |
| P99 | — | Top 1% |
How to calculate percentiles
Using linear interpolation:
1. Sort all your data in ascending order.
2. For a target value V, count how many values are ≤ V to get k.
3. Percentile = (k / n) × 100, where n is the total number of values.
Some methods use (k − 0.5)/n to reduce bias in small samples.
When to use percentiles and common mistakes
Frequently asked questions
What is a percentile?
A percentile shows what percentage of the data is less than or equal to a specific value. If you're at the 80th percentile, you rank higher than 80% of the group.
How do I calculate percentiles?
Sort your data in ascending order, count how many values are ≤ your target value, divide by the total count, and multiply by 100: Percentile = (count ≤ value / total) × 100.
What are quartiles?
Quartiles divide data into four equal parts: Q1 = 25th percentile, Q2 = 50th percentile (median), Q3 = 75th percentile. They show how data is distributed.
Is a high percentile good or bad?
It depends on context. For test scores and grades: high is good. For wait times or error rates: high is bad. Always consider what's being measured.
How many data points do I need?
At least 3–5 points for basic calculations, but results are more reliable with 20+ data points. With 30+ values, percentiles become statistically stable.
What is the interquartile range (IQR)?
The IQR = Q3 − Q1. It measures the spread of the middle 50% of your data and identifies outliers: values below Q1 − 1.5×IQR or above Q3 + 1.5×IQR.
What's the difference between percentile and percentage?
Percentage is any proportion (e.g., 25% of 100). Percentile refers to your relative ranking within a sorted group. The 80th percentile means you rank at position 80%.
How do I interpret my percentile rank?
Your percentile shows where you stand relative to others. The 75th percentile means you're in the top 25%, performing better than 75% of people or values in the group.