Percentages
Percentage change calculator
Compare an original value with a new value to find the percentage increase or decrease, using the original as your baseline.
How to calculate it
Subtract the original value from the new value, then divide the difference by the original. Multiply by 100 to get the percentage change. For example, a rise from 80 to 100 is an increase of 20, or 25% of the original 80. A negative answer means the value has decreased. When neither value is the original, use the percentage difference calculator to compare them against their average.
Worked examples
| Example | Working | Answer |
|---|---|---|
| 80 to 100 | (100 − 80) ÷ 80 × 100 | 25% |
| 100 to 80 | (80 − 100) ÷ 100 × 100 | −20% |
| 50 to 50 | (50 − 50) ÷ 50 × 100 | 0% |
| 200 to 250 | (250 − 200) ÷ 200 × 100 | 25% |
| 150 to 90 | (90 − 150) ÷ 150 × 100 | −40% |
| 10 to 10.5 | (10.5 − 10) ÷ 10 × 100 | 5% |
Frequently asked questions
Why can’t I start from zero?
The formula divides by the original value. Division by zero is undefined, so a percentage change from zero cannot be calculated with this formula.
Is percentage change the same as percentage points?
No. A rate moving from 10% to 15% rises by 5 percentage points, but by 50% relative to the original rate.
Can the original value be negative?
This tool requires a positive original value. Negative baselines can produce counterintuitive signs and need a context-specific interpretation.
How do I calculate percentage change in Excel or Google Sheets?
Use the formula =(new_value−old_value)/old_value, then format the cell as a percentage. For example, =(B2−A2)/A2 with the original value in A2 and the new value in B2.
What if the new value is zero?
A new value of zero gives a result of −100%, meaning the value has fallen to nothing. This is different from an original value of zero, which cannot be calculated because it would require dividing by zero.
Method: standard arithmetic. Examples are illustrative. How our calculators work.