Percentile Calculator

Percentile calculator at a glance#

A percentile is the value below which a given percent of the data falls. The 25th percentile is the value with 25 percent of the data below it. The percentile rank works the other way: it is the percent of values that fall below a particular value. To find a percentile rank, sort the data, count how many values are below your value, then divide by the total count and multiply by 100.

Worked example: in the sorted set 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 there are 10 values. The value 70 has 6 values below it, so its percentile rank is 6 / 10 times 100, which is the 60th percentile.

Enter your data in the calculator above to find the value at any percentile, or the percentile rank of a value. For percentiles that land between two data points, the calculator interpolates, so the result can differ slightly from other tools that round to the nearest data point.

How to find the value at a percentile#

The answer block above shows percentile rank (the percent of values at or below a number). Going the other way, finding the value that sits at a given percentile, takes one extra step. Sort the data, then find the position of the percentile with the index i = (p / 100) times (n + 1), where p is the percentile and n is the count. If i is a whole number, the value at that position is your answer. If it lands between two positions, interpolate between the two surrounding values.

Worked example#

Take seven scores: 55, 65, 76, 78, 84, 89, 90. For the 75th percentile, i = 0.75 times 8 = 6, so the answer is the 6th value, 89. For the 80th percentile, i = 0.80 times 8 = 6.4, which falls 0.4 of the way from the 6th value (89) to the 7th (90), so the result is 89 + 0.4 times 1 = 89.4. Calculators that round to the nearest data point would report 89 or 90 instead.

How to read the result#

A percentile tells you rank, not quality. The 90th percentile means 90 percent of the values are at or below that point, nothing more. A high or low percentile is not good or bad on its own; it depends on what the data measures. The 25th, 50th, and 75th percentiles (the quartiles) are the ones most often reported, because together they describe the spread of the middle half of the data.

Why two calculators can give different answers#

There is no single official percentile formula. Some tools use linear interpolation (the method this calculator uses), some round to the nearest rank, and some use variants like the exclusive or inclusive method found in spreadsheet functions. On small data sets these can differ by a value or two. The differences shrink as the data set grows. For a given report, pick one method and use it consistently.

Frequently asked questions#

What is a percentile?#

A percentile is the value below which a given percent of the data falls. The 30th percentile is the value with 30 percent of the data below it, which also means 70 percent of the data is above it.

What is the difference between a percentile and a percentile rank?#

A percentile is a value: the number at a given position in the sorted data. A percentile rank is a percentage: how many values fall at or below a number you choose. You compute one from the data position, the other from a value you supply.

How do you calculate the 95th percentile?#

Sort the data, then find the index i = 0.95 times (n + 1). If i is a whole number, take the value at that position. If not, interpolate between the two nearest values. The 95th percentile is common in performance monitoring, where it marks the value that 95 percent of measurements stay under.

Is the 50th percentile the same as the median?#

Yes. The 50th percentile is the median: the middle value, with half the data below and half above. For an even count, it is the average of the two middle values.

Can percentiles handle negative numbers and decimals?#

Yes. Sorting and interpolation work the same for negatives and decimals. Enter the values as they are; the calculator sorts them for you.