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.
Percentage Change Calculator
Runs entirely in your browser - no upload, no sign-up.
Old value to new value
+25%Increase
Difference: +10
(50 - 40) ÷ |40| × 100 = +25%
Results update as you type. Decimals (with a dot or a comma) and negative numbers are fine - nothing is uploaded.
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.
How to use
- 1Enter the original value. Type the starting or 'old' number in the first field - the baseline you are measuring from.
- 2Enter the new value. Type the final or 'new' number. The percentage change updates live and is labeled an increase or a decrease.
- 3Read 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.
FAQ
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.