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Percentile Range Calculator | Get Spread Between Two Percentiles

Compute the spread between any two percentiles — the interquartile range, P10–P90, or any custom band — with the interpolation shown. Understand the middle of your data and identify outliers with the 1.5×IQR rule.

Last updated: June 2026 · Free · No sign-up required

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Results

Enter values above and click Calculate to see your result instantly.

Quick reference

DataBandValuesRange
1–10P25–P753.25 / 7.754.5
1–10P10–P901.9 / 9.17.2
15, 20, 35, 40, 50P10–P9017 / 4629
Any dataP0–P100min / maxfull range

info Percentile Range Calculator

Free math calculator — enter your numbers and get an instant, accurate result.

info Private by design

Everything runs locally in your browser. No uploads, no accounts, no tracking.

info Works everywhere

Fully responsive and mobile-friendly — calculate on any device, any time.

info Educational

Includes the formula and step-by-step explanation so you understand the math, not just the answer.

Interpretation guide

BandWhat it captures
P25–P75 (IQR)Middle 50% — standard outlier-resistant spread
P10–P90Middle 80% — common in salary and growth charts
P5–P95Middle 90% — reference intervals in medicine
P2.5–P97.595% reference range, mirrors a 95% CI

lightbulb Worked example

Let's say you are using the Percentile Range Calculator. Computes the spread between any two percentiles of a data set — interquartile range, P10–P90 or any custom band. Enter the values that match your situation into the input fields and press calculate — using realistic numbers makes the result directly useful for you.

Result: The calculator instantly applies the formula Range = P(upper) − P(lower), percentiles by linear interpolation: h = (n−1)p/100, v = x⌊h⌋ + (h−⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋) and returns the result with appropriate precision.

What this means: Read the result in the context of what you are measuring. The step-by-step breakdown lets you confirm the math and understand which input most affects the outcome.

Formula & methodology

Formula: Range = P(upper) − P(lower), percentiles by linear interpolation: h = (n−1)p/100, v = x⌊h⌋ + (h−⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋)

The Percentile Range Calculator is built on a well-established calculation method. It uses the formula Range = P(upper) − P(lower), percentiles by linear interpolation: h = (n−1)p/100, v = x⌊h⌋ + (h−⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋) to turn your inputs into a reliable result. Computes the spread between any two percentiles of a data set — interquartile range, P10–P90 or any custom band. The steps are shown on the page so you can follow the reasoning from input to output.

  1. Paste your data set — at least two numbers, any separator.
  2. Pick the lower and upper percentiles (defaults 25 and 75 give the interquartile range).
  3. Values are sorted and each percentile is found by linear interpolation between the two nearest order statistics (the R-7 method, identical to Excel's PERCENTILE.INC).
  4. The range is simply the upper percentile minus the lower.

Worked example: data 1–10 with P25 and P75 → P25 = 3.25, P75 = 7.75, interquartile range = 4.5.

Authoritative source: Wolfram MathWorld

Frequently asked questions

What is a percentile range?
The Percentile Range Calculator is free, private, and accurate: it runs entirely in your browser (no uploads, no accounts), applies the standard calculation, and explains each step so you can verify the result. Computes the spread between any two percentiles of a data set — interquartile range, P10–P90 or any custom band. There is no limit on usage, and it works on any device.
How are the percentile values calculated?
Percentiles use linear interpolation: for the p-th percentile, compute the position h = (n − 1)p ÷ 100, then interpolate between the surrounding sorted values: v = x⌊h⌋ + (h − ⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋). This gives a continuous percentile definition that works for any data set size. The calculator shows the interpolation for your chosen percentiles.
Why use the IQR instead of the full range?
The full range only depends on the minimum and maximum, so a single outlier makes it misleading. The interquartile range (IQR), defined as P75 − P25, describes the spread of the middle half of the data and is robust to extreme values. Use the IQR for skewed data or when outliers are present, and reserve the full range for symmetric data without extremes.
What is the P10–P90 range used for?
The Percentile Range Calculator is a free online tool that computes the spread between any two percentiles of a data set — interquartile range, p10–p90 or any custom band. You enter a few values, and it returns an accurate result together with a step-by-step explanation, so it works as both a calculator and a quick reference for the underlying concept.
Can I compute a single percentile with this tool?
Yes — in addition to range modes like the IQR (P75 − P25) and P10–P90, the calculator accepts a single percentile value and returns it directly. Enter the percentile you need and the sorted data position and interpolated value are shown. This covers the common case of reporting a specific percentile like the median (P50) or the 95th.
What does the Percentile Range Calculator do?
Computes the spread between any two percentiles of a data set — interquartile range, P10–P90 or any custom band. The calculator takes your inputs, applies the standard calculation, and returns a clear result so you can make an informed decision without doing the math by hand.
What formula does the Percentile Range Calculator use?
The Percentile Range Calculator applies the standard formula: Range = P(upper) − P(lower), percentiles by linear interpolation: h = (n−1)p/100, v = x⌊h⌋ + (h−⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋). The tool walks through each step of the calculation so you can verify the numbers yourself.
Is the Percentile Range Calculator free and private?
Yes — the Percentile Range Calculator. There is no sign-up, no paywall, no trial, and no limit on how many calculations you can run. CalcaTools covers its costs with non-intrusive display advertising, so the calculator itself never asks for payment or restricts any feature.
How accurate is the Percentile Range Calculator?
The Percentile Range Calculator applies the standard formula: Range = P(upper) − P(lower), percentiles by linear interpolation: h = (n−1)p/100, v = x⌊h⌋ + (h−⌊h⌋)(x⌊h⌋₊₁ − x⌊h⌋). It is tested against published worked examples before launch and uses native double-precision arithmetic, so results are accurate to typical precision for the values you enter — with no intermediate rounding that could distort the answer.

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