Instantly find the percentage increase or decrease between any two numbers.
Calculate Percentage Change
The starting or "before" value
The ending or "after" value
What Is Percentage Change?
Percentage change measures how much a value has grown or shrunk relative to its original size. A positive result is an increase; a negative result is a decrease. It is one of the most widely used calculations in finance, science, and everyday life — from comparing prices to tracking weight loss.
The Formula
Percentage Change = ((New Value − Original Value) ÷ |Original Value|) × 100
The vertical bars around Original Value mean you use its absolute value (ignore the minus sign if it is negative). The result is expressed as a percentage.
Step-by-Step Examples
Example 1 — Price Increase
A jacket cost $80 last year and costs $100 this year.
Percentage change shows up constantly in daily decisions, not just in math class. Here are the situations where people reach for this calculator most:
Retail pricing: Retailers use it to set markups (cost → sale price) and to advertise discounts (original price → sale price). A shirt marked down from $40 to $28 is a 30% decrease.
Salary and budget reviews: HR teams and freelancers calculate the percentage change between last year's salary and this year's offer, or between last month's budget and actual spend, to spot variance quickly.
Investing and crypto: Traders track the percentage change of a stock or coin between the opening and closing price, or between two dates, to measure gains and losses without relying on dollar amounts alone.
Fitness and health tracking: Percentage change is used to express weight loss, strength gains (e.g., a lift going from 100 lb to 130 lb is a 30% increase), or changes in resting heart rate over a training block.
Business KPIs: Month-over-month or year-over-year revenue, traffic, and conversion rate comparisons are almost always reported as a percentage change rather than raw numbers, because it normalizes results across different scales.
Science and statistics: Researchers report percentage change in population counts, chemical concentrations, or experimental measurements between two conditions or time points.
Tips for Working with Percentage Change
Always divide by the original value, not the new one — this is the most common mistake. Going from 100 to 150 is +50%, but going from 150 back to 100 is −33.3%, not −50%.
Keep the sign. A negative result is a decrease, even if the calculator or spreadsheet drops the minus sign in a chart label — double-check before you present the number.
Don't add percentage changes across periods. A 10% increase followed by another 10% increase is not a 20% increase overall — it's 21% (1.10 × 1.10 = 1.21), because each change compounds on the new base value.
Round consistently. Two decimal places (e.g., 24.53%) is standard for finance and reporting; whole numbers are fine for quick estimates.
Use the reverse formula to sanity-check. If you know the percentage change and the new value, divide by (1 + percentage/100) to recover the original — useful for verifying invoices, tax-inclusive prices, or reported growth figures.
Common Percentage Change Reference Table
Original
New
Change
Direction
100
125
+25%
Increase
100
75
−25%
Decrease
50
100
+100%
Doubled
200
50
−75%
Decrease
1,000
1,500
+50%
Increase
80
80
0%
No change
Frequently Asked Questions
What is the formula for percentage change?
Percentage change = ((New Value − Original Value) ÷ |Original Value|) × 100. A positive result means an increase; a negative result means a decrease.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value to an original value with direction (increase or decrease). Percentage difference compares two values symmetrically, without a direction, using the average of the two values as the denominator.
What happens if the original value is zero?
Percentage change is undefined when the original value is zero, because you cannot divide by zero. If your original value is 0, consider using the absolute difference instead.
Can the percentage change exceed 100%?
Yes. For example, if a price goes from $50 to $150, that is a 200% increase. Percentage change has no upper or lower limit.
How do I reverse a percentage change?
To reverse a known percentage change back to the original value, divide the new value by (1 + percentage/100). For example, if $120 is a 20% increase, the original value is 120 ÷ 1.20 = $100.
Is a −50% change the same as a +50% change in reverse?
No. A 50% decrease followed by a 50% increase does not return to the original. Example: 100 → −50% → 50 → +50% → 75. The two moves are not symmetrical.
