Math & Scientific
Percent Change Calculator
Compare a strictly positive original value with a new value using signed percent change = (new − original) ÷ original × 100. The result identifies an increase, decrease or no change. The form takes two values; it does not take an amount and a percentage rate.
Give Percent Change Calculator your old value and new value and it returns the answer straight away. Built to solve a percentage question, it runs entirely on your device.
About this calculator
Compare a strictly positive original value with a new value using signed percent change = (new − original) ÷ original × 100. The result identifies an increase, decrease or no change. The form takes two values; it does not take an amount and a percentage rate.
How to use
- Enter a strictly positive original value and a finite new value. Zero or negative original values are outside this ordinary percentage-change model.
- Press Calculate to run the percent change calculator.
- Read the result: the percent change, the direction, and the absolute change.
- Press Reset to clear the percent change calculator and start again.
Why use Percent Change Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Based on standard, well-established formulas.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Use it when revising for exams
Percent Change in competitive-exam practice
Use it for verifying answers from a textbook
Use it for double-checking a spreadsheet result
Use it for science-fair and project numbers
Use it for understanding a formula's behaviour
Technical notes
Compare a strictly positive original value with a new value using signed percent change = (new − original) ÷ original × 100. The result identifies an increase, decrease or no change. The form takes two values; it does not take an amount and a percentage rate.
Inputs are taken exactly as entered, so check for typos before trusting an answer.
Because it runs locally, results appear instantly with no server round-trip.
FAQ
How is percent change calculated?
As (new − old) ÷ old × 100, so going from 100 to 120 is a 20% increase.
Does it show increases and decreases?
Yes. A positive signed result is an increase, a negative signed result is a decrease, and equal values are shown as no change. The absolute amount of the change is also displayed.
What do I enter in the Percent Change Calculator?
Enter a strictly positive original value and the new value. A zero or negative starting base is rejected; a negative new value is allowed and represents a decline through zero.
Does the Percent Change Calculator send my data to a server?
No — the Percent Change Calculator runs entirely in your browser, so the numbers you enter never leave your device.
Worked example
From 200 to 250: change = (250 − 200) ÷ 200 × 100 = +25%.