--- title: "Percentage Change Calculator - Free Online" description: "Free percentage change calculator: enter an old value and a new value to get the percent increase or decrease instantly, with the worked formula. Runs in your browser." url: https://candoya.com/tools/percentage-change/ locale: en type: browser-tool --- # Percentage Change Calculator Category: [Calculators](https://candoya.com/tools/calc/) ## What is a percentage change calculator? A percentage change calculator finds how much a value has risen or fallen in percent terms between an original and a new number. It uses (new - old) ÷ |old| × 100, labels the result an increase or a decrease, and shows the raw difference too - so you see both the percent and the amount. Everything runs **locally in your browser**. Your two numbers are never uploaded or stored, the result updates on every keystroke, and each answer shows the worked formula with your values substituted in - so you can check the math or reuse it by hand. It keeps working offline once the page has loaded. ## How to use it 1. **Enter the original value** - Type the starting or 'old' number in the first field - the baseline you are measuring from. 2. **Enter the new value** - Type the final or 'new' number. The percentage change updates live and is labeled an increase or a decrease. 3. **Read and copy the result** - The big number is the percent change; below it you get the raw difference and the worked formula. Use Copy to grab the percentage. ## Who it's for - **Investors and savers** measuring how much a price, portfolio, or balance moved up or down between two dates. - **Small-business owners** tracking month-over-month revenue, cost, or headcount change in percent terms. - **Students** checking percentage-change homework against the substituted formula, including negative and decimal values. - **Shoppers** seeing how much a price actually rose or fell, not just the raw difference in currency. - **Anyone comparing two numbers** - weight, mileage, followers, test scores - who wants the percent, not only the gap. ## Expert note Order matters and the base is the original value, so the calculation is not symmetric: going 40 to 50 is +25%, but 50 back to 40 is only -20%. That is why a 50% drop needs a +100% rise to fully recover - each step is measured against a different starting number. ## Frequently asked questions ### Is this percentage change calculator free? Yes - 100% free, no sign-up, and no limits. It runs entirely in your browser with plain JavaScript, so it also works offline once the page has loaded. ### Are my numbers uploaded anywhere? No. The math happens locally on your device. Nothing you type is sent to a server, stored, or shared - close the tab and the numbers are gone. ### How do you calculate percentage change? Subtract the old value from the new value, divide by the absolute old value, and multiply by 100: (new - old) ÷ |old| × 100. For example, from 40 to 50 that is (50 - 40) ÷ 40 × 100 = +25%, an increase. ### What is the difference between percentage increase and percentage decrease? They are the same formula; the sign tells you the direction. A positive result is a percentage increase (the value went up), a negative result is a percentage decrease (the value went down). This calculator labels each result for you. ### Why can't I use 0 as the original value? Percentage change divides by the original value, and dividing by 0 is undefined - there is no meaningful percent change from nothing to something. The calculator still shows the raw difference so the result is not useless. ### What is the difference between percent change and percentage points? Percent change is relative to the starting value; percentage points are the plain difference between two percentages. If a rate moves from 10% to 15%, that is 5 percentage points but a 50% increase - saying which you mean avoids a common misreading. ## Related tools - [Percentage Calculator](https://candoya.com/tools/percentage-calculator/) - [Z-Score Calculator](https://candoya.com/tools/z-score-calculator/) - [Perimeter Calculator](https://candoya.com/tools/perimeter-calculator/) - [Correlation Coefficient Calculator](https://candoya.com/tools/correlation-coefficient/) - [Compound Interest Calculator](https://candoya.com/tools/compound-interest/) --- *Markdown edition of , published for AI agents and other automated readers. Index of key pages: .*