What is a percentile?

A percentile is the value below which a given share of the data falls. If your score is at the 90th percentile, about 90 percent of the values sit at or below it. Example: in the set 78 to 95 a P90 of 93 means 90 percent of the scores are 93 or lower. Percentiles turn a raw number into a position, which is why they are used for test scores, growth charts and salary bands.

What are Q1, Q2 and Q3 (the quartiles)?

The quartiles cut sorted data into four equal parts. Q1 is the 25th percentile (a quarter of the values are below it), Q2 is the 50th percentile which is the median, and Q3 is the 75th percentile. For 1 to 10 with linear interpolation, Q1 is 3.25, Q2 is 5.5 and Q3 is 7.75. The middle 50 percent of your data lives between Q1 and Q3.

How do I calculate the IQR?

The interquartile range is simply IQR = Q3 − Q1, the spread of the middle half of the data. For 1 to 10 that is 7.75 − 3.25 = 4.5. IQR is a robust measure of spread because the extreme values do not move it the way they move the range or the standard deviation. A larger IQR means the middle of your data is more spread out.

How are outliers detected with the 1.5×IQR rule?

The Tukey rule marks any value below Q1 − 1.5×IQR or above Q3 + 1.5×IQR as an outlier. Take 10 11 11 12 12 12 13 13 14 15 100: the 100 sits far above the upper fence, so it is flagged. These fences are exactly the whisker limits on a box plot, which is why outliers show up as separate dots beyond the whiskers.

What is the difference between PERCENTILE.INC and PERCENTILE.EXC?

Inclusive (linear, R-7) places the percentile at position (n−1)·p, so P0 is the minimum and P100 is the maximum. Exclusive puts it at p·(n+1) and leaves the extreme tails undefined, which is why PERCENTILE.EXC cannot return the very smallest or largest value. For 1 to 10, P25 is 3.25 inclusive but 2.75 exclusive. Pick the method your assignment or software expects.

Is nearest-rank the same as the other methods?

No. Nearest-rank takes the value at rank ⌈p·n⌉ and never averages, so the answer is always a number that actually appears in your data. For 1 to 10 the nearest-rank P25 is 3, not the interpolated 3.25. It is the right choice when fractional results make no sense, for example picking a representative response-time sample rather than inventing one between two measurements.

Read where a test score sits in the class

A teacher pastes the whole class set and types 90 into the percentile box. The P90 tells them the cutoff above which the top tenth of students scored, and the quartiles split the class into four ability bands at a glance. Switch the percentile to find any rank — the 25th for the bottom quarter, the 50th for the median — without re-sorting the list by hand.

Set a salary band from market data

You have a column of comparable salaries and need a P25 to P75 range for an offer band. Paste the numbers, read Q1 and Q3, and the IQR shows how wide the middle of the market is. Because the calculator is robust to a couple of very high outliers, one executive package will not drag your band off the realistic center.

Flag latency outliers in a benchmark run

Paste a list of response times in milliseconds. The 1.5×IQR rule and the box plot immediately separate the normal cluster from a few slow spikes, so you can decide whether to investigate the tail or drop it before reporting a median. The five-number summary gives you min, Q1, median, Q3 and max in one line for the writeup.

Match a homework answer to the method your course uses

Stats courses disagree on quartile definitions, and a wrong method turns a correct calculation into a wrong grade. Toggle between linear (Excel INC), exclusive (Excel EXC) and nearest-rank to see all three answers side by side, then submit the one your textbook or software expects. The note under the result explains the difference.

Percentile Calculator with Quartiles, IQR and Outliers

Any percentile P plus Q1 Q2 Q3, IQR, five-number summary, box plot and 1.5×IQR outliers, browser-only

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Numbers (comma / space / newline separated)

Up to 10000 numbers. Integers, decimals, negatives, scientific notation (1.5e-3) accepted.

Try a preset

Percentile P

Interpolation method

P90 =92.1

Any value 0 to 100. Example: 90 gives the 90th percentile.

Inclusive linear interpolation. P0 returns the minimum, P100 the maximum. This is the default in NumPy, R and Excel’s PERCENTILE.INC.

Quartiles & IQR

Q1 (P25)

79.5

Q2 (P50, median)

85.5

Q3 (P75)

89.25

IQR (Q3 − Q1)

9.75

Five-number summary

Min

Q1 (P25)

79.5

Median

85.5

Q3 (P75)

89.25

Max

Box plot

Outliers (1.5×IQR rule)

Fences: [64.875, 103.875]

none

All numbers are computed in your browser tab. Nothing is uploaded or logged. The share URL does encode your data, so avoid sharing links for confidential numbers.

What this tool does

Free percentile and quartile calculator. Paste a list of numbers separated by commas, spaces or newlines and read any percentile P from 0 to 100, plus the full quartile set: Q1 (P25), Q2 (the median, P50), Q3 (P75) and the interquartile range IQR = Q3 − Q1. It also prints the five-number summary (min, Q1, median, Q3, max), draws a box plot, and flags outliers with the Tukey 1.5×IQR rule. Three interpolation methods are built in so the result matches whatever tool your class or report uses: linear (R-7, the NumPy and Excel PERCENTILE.INC default), nearest-rank (no averaging, always a real data point), and exclusive (Excel PERCENTILE.EXC). Everything runs in your browser, one-click copy and a shareable URL that reproduces your exact data and settings.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy + Preview; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Student; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Percentile Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Read where a test score sits in the class
A teacher pastes the whole class set and types 90 into the percentile box. The P90 tells them the cutoff above which the top tenth of students scored, and the quartiles split the class into four ability bands at a glance. Switch the percentile to find any rank — the 25th for the bottom quarter, the 50th for the median — without re-sorting the list by hand.
Set a salary band from market data
You have a column of comparable salaries and need a P25 to P75 range for an offer band. Paste the numbers, read Q1 and Q3, and the IQR shows how wide the middle of the market is. Because the calculator is robust to a couple of very high outliers, one executive package will not drag your band off the realistic center.
Flag latency outliers in a benchmark run
Paste a list of response times in milliseconds. The 1.5×IQR rule and the box plot immediately separate the normal cluster from a few slow spikes, so you can decide whether to investigate the tail or drop it before reporting a median. The five-number summary gives you min, Q1, median, Q3 and max in one line for the writeup.
Match a homework answer to the method your course uses
Stats courses disagree on quartile definitions, and a wrong method turns a correct calculation into a wrong grade. Toggle between linear (Excel INC), exclusive (Excel EXC) and nearest-rank to see all three answers side by side, then submit the one your textbook or software expects. The note under the result explains the difference.

Common pitfalls

Assuming every tool gives the same quartiles. Excel PERCENTILE.INC, PERCENTILE.EXC and textbook methods can all return different Q1 values for the same data. Check which method your course or software uses and switch the calculator to match before comparing answers.
Confusing percentile value with percentile rank. P90 is the value at the 90th position; the percentile rank answers the reverse question, what percent of data falls below a given value. Typing a data value into the percentile box returns the wrong thing.
Reading IQR as the full range. IQR is only the middle 50 percent, Q3 − Q1, not max − min. A small IQR with a large range means the data is tightly packed in the middle but has a few far-out tails, which the box plot shows clearly.

Privacy

Every percentile, quartile and outlier check is plain JavaScript that runs in your browser tab; no data is uploaded or logged. One caveat: the shareable link encodes your numbers, the chosen percentile and the method in the URL, so a link pasted into chat records those numbers in the recipient server access log. For confidential scores or salaries, use the copy button and paste the text instead of sharing the URL.

FAQ

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Percentile Calculator with Quartiles, IQR and Outliers

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Percentile Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Read where a test score sits in the class

Set a salary band from market data

Flag latency outliers in a benchmark run

Match a homework answer to the method your course uses

Common pitfalls

Privacy

FAQ

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