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Percentage Change Calculator

Calculate percentage change, amount of change, ratio and multiplier from before and after values. Reverse calculation and batch processing are also supported.

Last updated: 2026/10/16 Calculator Feedback & bug reports
Change Rate —
Amount of Change —  
Ratio —  
Multiplier —  

How to Use

1

Enter before and after values

In the "Find Change Rate" tab, enter the old value and the new value — for example last year vs this year, or list price vs sale price.

2

Check the results

As you type, the change rate (%), amount of change, ratio and multiplier are calculated automatically in real-time.

3

Use reverse & batch modes

Use "Find Value" to derive a value from a change rate, or "Batch Calculate" to process many rows of data at once.

About the Percentage Change Calculator

A tool that instantly calculates the percentage change (rate of change) between two values — how much something increased or decreased. It handles year-over-year growth, achievement rates, discount rates and other common ratio calculations for business and daily life. Everything runs in your browser, so your numbers are never sent to a server.

Features

  • Real-time CalculationChange rate, amount, ratio and multiplier appear the moment you type. No waiting.
  • Reverse CalculationDerive the resulting value from a base value and a change rate — perfect for discounts and target values.
  • Batch ProcessingPaste "before, after" rows to calculate and copy change rates for many items in a table at once.
  • Privacy ProtectedAll processing happens in your browser. Your numbers are never sent to any server.

Use Cases

  • Growth rate of sales and KPIs (YoY, MoM)
  • Discount rate from list price to sale price
  • Achievement and progress rate against a target
  • Change rate of stock prices, weight, traffic and more
  • Compare change rates across many items or periods at once

FAQ

How is the percentage change calculated?
Using "(new value − old value) ÷ |old value| × 100". For example, going from 100 to 125 gives +25%.
How is it different from the ratio (year-over-year)?
The ratio is "new ÷ old × 100" (125% for 100→125), while the change rate is that minus 100% (+25%). This tool shows both at once.
Can it calculate discount rates?
Yes. Enter the list price as "before" and the sale price as "after"; the change rate appears as a negative value (e.g. −20%), which is the discount rate. Conversely, enter -20 in "Find Value" to get the discounted price.
What happens when the before value is 0?
A change from 0 cannot be expressed as a ratio, so the change rate, ratio and multiplier show "—". The amount of change (difference) is still calculated normally.
Is my data stored or sent anywhere?
No. All calculations run locally in your browser, and your numbers are never sent to or stored on any server.

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