Percentile Calculator

About the Percentile Calculator

The Percentile Calculator finds the value at any given percentile in your data set, or the percentile rank of any given value. The kth percentile is the value below which k% of the data falls.

Percentiles are widely used in standardized testing (SAT scores), pediatric growth charts, income distribution, and performance benchmarking. The 50th percentile is the median, 25th is Q1, and 75th is Q3.

This calculator accepts comma-separated data, computes the requested percentile using linear interpolation, and provides a complete quartile summary. Enter your data and a target percentile to get started.

When This Page Helps

Finding exact percentiles requires sorting, ranking, and interpolation. This calculator handles all the math and provides a complete quartile summary.

How to Use the Inputs

1. Enter your data set separated by commas.
2. Enter the desired percentile (0–100).
3. View the value at that percentile.
4. See the full quartile summary (Q1, Q2, Q3).
5. Or enter a specific value to find its percentile rank.

Example Calculation

Tips & Best Practices

• The 50th percentile equals the median.
• The 25th and 75th percentiles are Q1 and Q3; IQR = Q3 − Q1.
• Different software uses different interpolation methods; results may vary slightly.
• A percentile rank of 90 means you scored better than 90% of the group.
• Percentiles are not the same as percentages on a test.
• Growth charts use percentiles to track child development over time.

Percentiles in Standardized Testing

SAT, GRE, and ACT scores are reported with percentile ranks so you can compare across different test dates and versions. A 1200 SAT at the 75th percentile means you beat 75% of test-takers.

Percentiles in Health

BMI, blood pressure, and growth charts use percentiles to identify typical versus unusual values. Values below the 5th or above the 95th percentile often trigger further evaluation.

Box Plots and Quartiles

Box plots visualize Q1, median, Q3, and outliers. The box spans the IQR, and whiskers extend to 1.5 × IQR. Points beyond that are plotted as individual outliers.

Frequently Asked Questions

• What is a percentile?

  The kth percentile is the value below which k% of the data falls. The 90th percentile means 90% of values are at or below that point.

• What is percentile rank?

  Percentile rank is the percentage of values in the data set that are less than or equal to a given value. If your score is at the 85th percentile rank, you scored higher than 85% of the group.

• What are quartiles?

  Quartiles divide data into four equal parts. Q1 (25th percentile), Q2 (50th, median), and Q3 (75th percentile). The IQR = Q3 − Q1 measures the middle 50%.

• Are there different methods for computing percentiles?

  Yes, there are multiple methods (inclusive, exclusive, interpolation). Different tools may give slightly different results for the same percentile, especially with small data sets.

• What is the difference between percentile and percentage?

  A percentage is a fraction of a total (e.g. 80% correct). A percentile is a ranking among peers (e.g. 80th percentile means better than 80% of scores). They measure different things.

• How are percentiles used in growth charts?

  Pediatricians plot a child's height and weight against age-based percentiles. A child at the 75th percentile for height is taller than 75% of children the same age.