Percentage Change Calculator
Enter an old value and a new value to find the percentage increase or decrease, the absolute change, and the ratio between the two numbers.
How to use
- Enter the original or old value in the first field.
- Enter the new or updated value in the second field.
- Click Calculate to see the percentage change, absolute difference, and ratio.
- Use Reset to clear the form and start over.
When people use this
- Comparing sales, revenue, or traffic between two periods.
- Checking price changes — did a product go up or down, and by how much?
- Measuring performance improvements or declines (test scores, productivity, etc.).
- Calculating inflation or deflation between two values.
- Analysing population, weight, or any numeric change over time.
Examples
Example 1: Old: 50, New: 75 → +50.00% increase, absolute change +25, ratio 1.50, +25 percentage points.
Example 2: Old: 120, New: 90 → −25.00% decrease, absolute change −30, ratio 0.75, −30 percentage points.
Example 3: Old: 80, New: 80 → 0.00% no change, absolute change 0, ratio 1.00.
Example 4: Old: 1000, New: 1200 → +20.00% increase, absolute change +200, ratio 1.20.
FAQ
Q: How is percentage change calculated?
A: Percentage change = ((new − old) ÷ old) × 100. A positive result means an increase; a negative result means a decrease. If the old value is zero, the percentage change is undefined.
Q: What is the difference between percentage change and percentage points?
A: Percentage change is relative: ((new−old)/old)×100. Percentage points is the absolute difference: new−old. For example, going from 20% to 25% is a 5 percentage point increase but a 25% relative increase.
Q: What happens if the old value is zero?
A: Percentage change is undefined when the old value is zero — you cannot divide by zero. The calculator will show an error and ask you to enter a non-zero old value.
Q: Can the values be negative?
A: Yes — the calculator works with negative numbers. For example, going from −10 to −5 is a 50% increase (the value moved towards zero).
Q: What does the ratio mean?
A: The ratio new/old tells you how many times the new value is relative to the old. A ratio of 1.5 means the new value is 1.5× the old (a 50% increase). A ratio of 0.75 means the new value is 75% of the old (a 25% decrease).