Percentage Change Calculator

Work out the percentage increase or decrease between two values.

Original value New value

—change

—absolute difference

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About the Percentage Change Calculator

This works out the percentage increase or decrease between two numbers — an old value and a new one. It's the tool for comparing before and after: a price rise or drop, a change in salary, a jump or fall in website traffic, a stock or portfolio move, or quarter-on-quarter growth. Enter the original and new values and it shows the percentage change and whether it's an increase or decrease.

How it works — the formula

Percentage change = (new − old) ÷ |old| × 100.

The difference between the two values is divided by the original value, then turned into a percentage. A positive result is an increase, a negative one a decrease. For example, going from 120 to 150 is (150 − 120) ÷ 120 × 100 = +25%; going from 150 to 120 is −20%. The original value is always the base, which is why the two directions give different percentages.

Assumptions and behaviour

The original value is the base for the percentage — change is measured relative to where you started.
A positive result is labelled an increase, negative a decrease.
It also shows the plain absolute difference (new − old).
Negative and decimal values are accepted.

Limitations

Change from zero is undefined. If the original value is 0, dividing by it has no answer — there's no meaningful "percentage increase from nothing" — so the tool shows a dash.
The two directions aren't symmetric. A rise from 100 to 150 is +50%, but the fall back from 150 to 100 is −33.3%, because the base changes. That's correct, not a bug.
Percentage points aren't the same as percent — a rate moving from 5% to 7% is a 2-point rise but a 40% increase. This tool computes the relative change you enter.
Results are rounded for display.

Privacy

The calculation runs entirely in your browser. Nothing is uploaded or stored.

Frequently asked questions

Is this percentage change calculator free?

Yes — free, no sign-up, no limits, runs in your browser.

How do I calculate percentage change?

Subtract the old value from the new, divide by the old value, and multiply by 100. From 120 to 150 is (150−120)÷120×100 = +25%.

Why is a rise and the matching fall different percentages?

Because the base changes. 100 to 150 is +50%, but 150 back to 100 is −33.3% — each is measured against its own starting value.

Why does it show a dash when the original is 0?

Percentage change divides by the original value, and dividing by zero is undefined — there's no meaningful percentage increase from nothing.

What's the difference from a percentage-of calculation?

This measures how much a value changed relative to its starting point. Finding X% of a number, or what percent one number is of another, is handled by the Percentage Calculator.

Does it handle negative numbers?

Yes. Negative and decimal values are accepted; the base uses the magnitude of the original value.

Is my data uploaded?

No. Everything runs locally in your browser; nothing is sent or stored.

Written by Lakshay Kumar(TechLakshay)

A QA Automation Engineer by trade, Lakshay's real passion is untangling complex problems into simple, working solutions — which is exactly why FreeMyTask exists. On Instagram, he channels that same instinct into helping 26,000+ content creators with SEO education, motivation, and hands-on query solving.

Last updated: August 22, 2026