Ever noticed how prices go up or down, your test scores improve (hopefully!), or your social media followers spike overnight? Those are all changes—and knowing how to calculate the percentage change helps you see how much something increased or decreased.
Let’s make it super simple. 
Table of Contents
What Is Percentage Change?
Percentage change tells you how much something has increased or decreased compared to where it started.
Think of it like this:
“My score went from 70 to 84. How big of an improvement is that?”
Answer: Let’s find out with percentage change!
The Formula for Percentage Change
Here’s the go-to formula:
Percentage Change = [(New Value - Old Value) / Old Value] × 100You’ll get:
- A positive percentage if it increased
- A negative percentage if it decreased
Let’s Do a Quick Example
Your electricity bill went from $100 last month to $120 this month.
Change = 120 - 100 = 20
Percentage Change = (20 / 100) × 100 = 20%
Your bill increased by 20%
What If It Decreased?
Say your phone data usage went from 10GB to 7GB.
Change = 7 - 10 = -3
Percentage Change = (-3 / 10) × 100 = -30% Your data decreased by 30
Percentage Change Calculator
Enter the New Value, Original Value and the tool will provide the percentage change
Quick Recap
| Term | Meaning |
|---|---|
| Old Value | The original amount |
| New Value | The updated amount |
| Positive Result | It went up (increase) |
| Negative Result | It went down (decrease) |
Pro Tips
- Always divide by the old/original value.
- Round to 1 or 2 decimal places if needed.
- Use it for tracking prices, budgets, weight changes, grades—you name it!
Final Thoughts
Percentage change is one of those life skills that comes in handy all the time. Whether you’re managing money, improving your fitness, or just curious about growth, now you know exactly how to calculate it.
So next time someone says, “It increased by how much?!” — you can show them the math! 