How to Calculate Percentage Change: A Complete Guide
Whether you are tracking stock performance, measuring business growth, or analyzing scientific data, calculating percentage change is essential. Here is exactly how to do it.
Try it: Percentage Change Calculator
Enter any two values and instantly see the percent change, growth factor, and reverse calculation.
Percentage Change Calculator
How Percentage Change Works
Find the Difference
Subtract the original value from the new value.
Divide by Original
Divide the difference by the absolute original value.
Multiply by 100
Convert to a percentage by multiplying by 100.
Common Applications
- Price changes: How much did a stock or product price increase?
- Growth rates: Revenue growth, population growth, or user growth
- Performance: Test score improvement, weight loss/gain percentage
- Budget variance: Actual vs. planned spending differences
The full calculator also supports multi-period change and chained percent changes.
Open the full math calculatorQuick Answer: Common Percentage Changes
Sign convention: positive = increase, negative = decrease. The formula is ((New − Old) / |Old|) × 100:
| From → To | Change | Formula |
|---|---|---|
| $80 → $100 | +25% | ((100 − 80) / 80) × 100 |
| $200 → $150 | −25% | ((150 − 200) / 200) × 100 |
| $50 → $75 | +50% | ((75 − 50) / 50) × 100 |
| $1,000 → $1,250 | +25% | ((1250 − 1000) / 1000) × 100 |
| −10 → +5 | +150% | ((5 − (−10)) / |−10|) × 100 |
Note: percentage change is not symmetric — going from $100 to $80 is −20%, but going from $80 back to $100 is +25%. The reference value matters.
The Percentage Change Formula
Percentage Change = ((New Value - Old Value) / |Old Value|) x 100
A positive result means increase. A negative result means decrease.
Example: Stock Price Increase
If a stock goes from $50 to $65:
((65 - 50) / 50) x 100 = (15 / 50) x 100 = 0.3 x 100 = +30%
The stock price increased by 30%.
Example: Price Decrease
If a product drops from $200 to $150:
((150 - 200) / 200) x 100 = (-50 / 200) x 100 = -0.25 x 100 = -25%
The price decreased by 25%.
Why Use Absolute Value for the Old Value?
Using the absolute value of the old value ensures the calculation works even when the old value is negative. For example, going from -10 to +5: ((5 - (-10)) / |-10|) x 100 = (15/10) x 100 = +150%.
Common Percentage Change Scenarios
| Scenario | From to To | Change |
|---|---|---|
| Revenue growth | $100K to $150K | +50% |
| Population change | 1M to 1.2M | +20% |
| Weight loss | 200 lbs to 180 lbs | -10% |
| Test score improvement | 72% to 85% | +18.1% |
Key Takeaways
- The percentage change formula works for any two values
- A positive result means increase; negative means decrease
- Always use the absolute value of the original value as the denominator
- Use our Percentage Change Calculator for instant results