📈 Percentage Change Calculator

Use this percentage change calculator to find the percent increase or decrease between two numbers. Enter a starting value and an ending value to see the percentage change, the absolute difference, and whether the change is an increase, decrease, or no change.

Percentage change results

Enter a starting value and an ending value, then choose Calculate Percentage Change to see the percentage increase or decrease, the absolute change, and how many times larger or smaller the ending value is compared to the starting value.

Percentage change breakdown for your values

Once you calculate a result, this section shows the inputs, absolute change, percentage change, direction of change, and the ending value as a multiple of the starting value. This makes it easier to copy the details into reports or spreadsheets.

Percentage change inputs and key terms

This calculator focuses on percent change, which compares how much a value has increased or decreased relative to its starting point. Here is how each input and output is used.

• Starting value: The original number before the change. Examples include last year's revenue, a previous exam score, or yesterday's stock price.
• Ending value: The new number after the change. Examples include this year's revenue, your latest exam score, or today's stock price.
• Absolute change: The simple difference between the ending and starting values ( ending value − starting value). This shows how much the value changed in the original units.
• Percentage change: The size of the change relative to the starting value, expressed as a percentage. This makes it easier to compare changes across different scales.
• Increase vs. decrease: If the ending value is larger than the starting value, the percent change is positive and represents an increase. If it is smaller, the percent change is negative and represents a decrease.
• Ratio (ending vs. starting): Shows how many times larger or smaller the ending value is compared to the starting value. For example, a ratio of 1.50 means the ending value is 1.5 times the starting value.
• Undefined percent change when starting value is zero: Because percent change divides by the starting value, the calculation does not work when the starting value is 0. In those cases, it is better to describe the change using the absolute difference instead of a percentage.

Formulas used in the Percentage Change Calculator

This calculator uses standard percent change formulas you'll see in business reports, grade calculations, finance, and everyday comparisons.

1. Absolute change

Let X be the starting value and Y be the ending value.
Absolute change = Y − X
A positive result means the value went up; a negative result means it went down.

2. Percentage change

Percent change scales the absolute change by the size of the starting value:
Percent change = (Y − X) ÷ X × 100%
This formula answers “By what percent did the value change relative to where it started?”

Example: If a value increases from 80 to 100:
Absolute change = 100 − 80 = 20
Percent change = (20 ÷ 80) × 100% = 25%
This is a 25% increase.

3. Direction of change

• If Percent change > 0 → increase
• If Percent change < 0 → decrease
• If Percent change = 0 → no change

4. Ratio of ending value to starting value

The calculator also shows how many times the ending value is compared to the starting value:
Ratio = Y ÷ X
A ratio of 2.0 means the ending value is twice as large; a ratio of 0.5 means it is half as large.

These formulas are widely used in financial statements, analytics dashboards, grade reports, and performance metrics, which is why they are helpful to understand and double-check.

Percentage Change Calculator FAQs

• What is the difference between absolute change and percentage change?
  Absolute change is simply the difference between the ending and starting values (ending − starting). Percentage change compares that difference to the starting value and expresses it as a percentage. Percentage change is more useful when you want to compare changes across different scales or contexts.
• Why does percent change get very large when the starting value is small?
  Because percent change divides by the starting value, any change relative to a very small starting value becomes a large percentage. For example, going from 1 to 3 is only a change of 2 units, but it is a 200% increase. When the starting value is tiny, it is often more intuitive to talk about the absolute change instead of the percent change.
• Can I use this calculator for prices, grades, and performance metrics?
  Yes. Percentage change is commonly used for price changes (sales, discounts, markups), grade improvements, and performance metrics such as website traffic, sales volume, and conversion rates. Just make sure the starting value and ending value represent the same unit and context.
• How is a 50% decrease different from a 50% increase?
  A 50% increase multiplies the starting value by 1.5, while a 50% decrease multiplies it by 0.5. If you increase something by 50% and then decrease the new value by 50%, you do not return to the original number—you end up lower because the second 50% is applied to a larger or smaller base.
• How accurate are the results, and how should I round them?
  This calculator uses standard floating-point math and typically shows two decimal places for percentage results. In practice, you can round to whole percentages or one decimal place depending on your reporting needs. The key is to be consistent with your rounding rules across similar calculations.
• Why is percent change often used in reports and dashboards?
  Percent change makes it easier to compare changes across different metrics and scales. For example, a $10,000 increase in revenue might be huge for a small business but minor for a large one. Percentage change normalizes the difference so stakeholders can quickly see how meaningful the change is relative to where they started.