Have you ever wanted to know how much something increased or decreased? Whether you’re a student trying to understand math, a shopper comparing prices, or an adult looking at bills or earnings, knowing how to calculate percentage change can help. It’s a simple way to compare two numbers — like a before and after — and see the difference as a percent.
To make your life easier, you can also use a percentage calculator to save time and avoid mistakes.
What Is Percentage Change?
Percentage change tells you how much something has increased or decreased, compared to the original amount. It gives you a clear view of growth or drop in numbers.
For example:
- If your weekly allowance goes from $10 to $15, that’s an increase.
- If a product’s price goes from $50 to $40, that’s a decrease.
We use percentage change to show this difference using a percent sign (%).
Formula to Find Percentage Change
The basic formula to find percentage change is:
Percentage Change = (Difference / Original Number) × 100
Let’s break this down:
- Find the difference between the two numbers (new value – original value).
- Divide that difference by the original number.
- Multiply the result by 100 to get the percentage.
Now, let’s see how this works with simple examples.
Example 1: Increase in Number
Let’s say a student scored 60 marks in the first test and 75 marks in the second test. What is the percentage increase?
Step-by-step:
- Difference = 75 – 60 = 15
- Original Number = 60
- Percentage Change = (15 / 60) × 100 = 25%
✅ The score increased by 25%.
You can double-check this using a simple online percentage calculator.
Example 2: Decrease in Number
Let’s say you were spending $200 per month on groceries, and now you spend $150.
Step-by-step:
- Difference = 200 – 150 = 50
- Original Number = 200
- Percentage Change = (50 / 200) × 100 = 25%
✅ The spending decreased by 25%.
Again, you can use a percentage difference calculator to quickly get this result without doing the math manually.
Important Note: Always Use the Original Value
When using the formula, always divide by the original number. This is key. Many people make mistakes by dividing by the new number. That will give you the wrong percentage.
Real-Life Examples of Percentage Change
1. Shopping Discounts
You see a jacket that was $100, but now it’s $75. What’s the percentage discount?
- Difference = 100 – 75 = 25
- Original Price = 100
- (25 / 100) × 100 = 25%
✅ You got a 25% discount on the jacket.
You can also plug these numbers into a percentage calculator to check instantly.
2. Salary Increase
You earned $3,000 per month last year. Now you earn $3,300. What’s the raise in percent?
- Difference = 3,300 – 3,000 = 300
- Original = 3,000
- (300 / 3,000) × 100 = 10%
✅ You got a 10% salary increase.
This is a common use of percentage change in the workplace.
3. School Grades
Your last math test score was 80. This time you scored 60. What’s the percentage change?
- Difference = 80 – 60 = 20
- Original = 80
- (20 / 80) × 100 = 25%
✅ This is a 25% decrease in score.
Don’t forget, if math isn’t your strong point, you can always use a calculate percentage tool online to save time.
Percentage Increase vs. Percentage Decrease
Here’s a quick guide to help:
| Situation | Result |
| New number is more | Percentage Increase |
| New number is less | Percentage Decrease |
| No change | 0% Change |
Common Mistakes to Avoid
- Using the new value instead of the original
Always divide by the original number. - Forgetting to multiply by 100
Without this, you won’t get a percentage. - Mixing up positive and negative changes
A drop is a negative change; a rise is positive.
Shortcut Tip
If you’re in a hurry and want quick results, especially for business reports, school assignments, or shopping comparisons, a simple online percentage calculator can give you the correct number fast.
These tools are mobile-friendly and save you from doing manual calculations.
Summary
To find the percentage change between two numbers:
- Subtract the original number from the new number.
- Divide that by the original number.
- Multiply by 100.
This gives you the percentage increase or decrease. It’s a simple and useful skill for everyday life.
And remember, a percentage calculator is always there if you want a quick and accurate result!
FAQs
1. What is the difference between percentage change and percentage difference?
Answer:
Percentage change shows how much a number has increased or decreased from its original value.
Percentage difference compares two values and tells how far apart they are in percentage, without focusing on which is original or new.
You can try both with a percentage difference calculator.
2. Why do we use percentage change in real life?
Answer:
We use percentage change to track growth, drops, or trends — like price changes, salary hikes, test scores, business profits, and more. It helps us compare numbers fairly, no matter how big or small they are.
3. Can I use this method for negative numbers or decimals?
Answer:
Yes! The same formula works with negative numbers and decimals. Just be careful with signs. A negative result means a decrease, and a positive one means an increase.
If in doubt, use a calculate percentage tool to avoid errors.