Calculate a change (rate of change) as a percentage

Increase/Decrease From: To:
Percent of Gain:

Understand What Percentage Change Means and When to Use It

Percentage change shows how much a value has increased or decreased compared to its original amount. It is expressed as a percentage and helps you quickly understand the size of a change in relation to the starting value.

You can calculate percentage change using this formula:

Percentage Change = ((New Value - Original Value) / Original Value) × 100

The result will be:

  • Positive — if the new value is higher (an increase).
  • Negative — if the new value is lower (a decrease).

This is useful in many everyday situations, such as:

  • Tracking price increases or discounts when shopping
  • Measuring changes in income or expenses
  • Analyzing performance in business or finance
  • Understanding weight changes over time

Using a percentage makes it easier to compare changes across different values or time periods.

Common Real-Life Examples Like Price Increases, Discounts, or Value Drops

Percentage change is all around us. Here are some common situations where it’s useful:

  • Price Increases:
    A product used to cost $50 and now it costs $60. You can calculate the percentage increase to see how much more you're paying.
  • Discounts:
    A jacket was originally $80 and is now on sale for $60. Use the percentage change to find out how big the discount is.
  • Value Drops:
    A car you bought for $15,000 is now worth $12,000. Calculating the percentage decrease tells you how much value it lost.
  • Salary Changes:
    If your salary increased from $3,000 to $3,300, the percentage change tells you how much more you’re earning.
  • Utility Bills:
    Your electricity bill went from $100 last month to $120 this month. Calculate the percentage increase to monitor your usage or costs.

These examples help you make better financial decisions and understand changes more clearly.

How to Use the Calculator

This calculator helps you find the percentage change between two numbers. Follow these simple steps:

  1. Enter the original value in the "Increase/Decrease From" field.
    Example: If a product was originally $50, type 50.
  2. Enter the new value in the "To" field.
    Example: If the new price is $65, type 65.
  3. Click the "Calculate Gain" button.
    The calculator will display the percentage change in the "Percent of Gain" field.
  4. If you want to start over, click the "Clear All Fields" button to reset everything.

That’s it! In just a few clicks, you can find out how much something increased or decreased as a percentage.

Explanation of Each Field

Here's what each input field in the calculator means:

“From” Value

This is the original value before the change occurred. For example, if a product used to cost $40, then "40" is your "From" value.

“To” Value

This is the new value after the change. If the product’s new price is $50, then "50" is your "To" value.

“Percent of Gain”

This field shows the result — the percentage change between the "From" and "To" values. A positive percentage means an increase; a negative percentage means a decrease.

For example, if the price went from $40 to $50, the calculator will show: 25%. This means the price increased by 25%.

What Does the Result Mean?

The result you see in the “Percent of Gain” field tells you how much the value has changed in percentage terms.

Here's how to interpret the result:

  • Positive Percentage (e.g., 20%)
    This means there has been an increase from the original value.
    Example: If something went from 100 to 120, the result will be 20%, showing a 20% increase.
  • Negative Percentage (e.g., -15%)
    This means there has been a decrease from the original value.
    Example: If something went from 200 to 170, the result will be -15%, showing a 15% decrease.
  • 0%
    This means there is no change between the original and new values.

Whether you're tracking prices, performance, or costs — this percentage helps you quickly understand the size and direction of the change.

Examples

Example of a Gain (Increase)

Let’s say the price of a concert ticket increased from $80 to $100.

  • From: 80
  • To: 100

Use the calculator to find the percentage change:

((100 - 80) / 80) × 100 = 25%

Result: 25% gain — the ticket price increased by 25%.

Example of a Loss (Decrease)

Imagine the value of a smartphone dropped from $600 to $480.

  • From: 600
  • To: 480

Use the calculator to find the percentage change:

((480 - 600) / 600) × 100 = -20%

Result: -20% loss — the phone's value decreased by 20%.

Tips for Accurate Results

✅ Double-Checking Your Inputs

Always make sure you've entered the correct values:

  • Type numbers only — avoid symbols like $ or %.
  • Enter the original amount in the "From" field.
  • Enter the new or updated amount in the "To" field.
  • Check for typos or misplaced digits before clicking "Calculate Gain".

⚠️ Common Mistakes to Avoid

  • Swapping the "From" and "To" values — this will give the wrong result.
  • Leaving a field blank — both fields must be filled for the calculator to work.
  • Using commas in numbers (e.g., writing 1,000 instead of 1000).
  • Trying to calculate a percentage change from zero — this is not allowed, as it causes division by zero.

❓ What If the Result is 0%?

A result of 0% means there has been no change between the original value and the new value.

Example: If something cost $75 before and still costs $75 now, the calculator will show:

0%

This tells you the value stayed the same — no gain or loss occurred.

Frequently Asked Questions (FAQs)

❓ What does a negative percentage mean?

A negative percentage means the value has decreased. For example, if your value drops from 200 to 150, the calculator will show -25%.

❓ Can I use decimal numbers?

Yes, you can enter decimal values like 99.5 or 120.75 for more precise results.

❓ Why is my result showing NaN or blank?

This usually happens if:

  • You left one or both input fields empty
  • You entered non-numeric characters (like $ or letters)
  • You used 0 as the "From" value — division by zero is not allowed

❓ What if I enter the same number in both fields?

If the "From" and "To" values are the same, the result will be 0%, meaning there's no change.

❓ Can I use this for negative numbers?

Technically yes, but keep in mind the context. For most everyday use (like prices or measurements), values are usually positive. If you're comparing debts or temperature drops, it might make sense — just interpret results carefully.

❓ Is the percentage always rounded?

Yes, this calculator rounds the result to two decimal places for simplicity and readability.

OTHER CALCULATORS