Percentage Change Calculator
Find the percentage increase or decrease between any two numbers, with the formula.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this percentage change calculator
- Enter the starting value (from) in the first field.
- Enter the ending value (to) in the second field.
- Press Calculate to see the percentage change and direction.
- Use Copy to put the result on your clipboard, or Reset to clear the inputs.
About this percentage change calculator
The percentage change calculator measures how much a value has moved between two points in time, expressed as a percentage of the original. A positive result is an increase; a negative result is a decrease.
The formula is ((to − from) ÷ |from|) × 100. Taking the absolute value of the starting number means the direction of the change is encoded by the sign of the result rather than depending on whether the original value was positive or negative. For example, if a stock moves from 80 to 100, the change is ((100 − 80) ÷ |80|) × 100 = (20 ÷ 80) × 100 = 25%, so it has risen 25%. A move from 100 to 80 is ((80 − 100) ÷ |100|) × 100 = −20%, a 20% decrease.
This is the standard percent change calculation used in finance, statistics, science, and everyday comparisons — useful for sales growth, price differences, exam-score deltas, and tracking any before-and-after pair of numbers.
FAQ
- What does the percentage change calculator compute?
- It returns the percentage difference between a starting value (from) and an ending value (to). A positive percentage is an increase; a negative percentage is a decrease.
- What is the percent change formula?
- Percent change equals ((to − from) ÷ |from|) × 100. The vertical bars mean absolute value, so a positive percentage always indicates an increase regardless of the sign of the starting value.
- What happens if the starting value is zero?
- The tool returns an error. Percentage change is undefined when the starting value is zero because the formula would divide by zero. Use the absolute difference (to − from) instead in that case.
- How is this different from a regular percentage calculator?
- A general percentage calculator answers "X% of Y" or "X is what % of Y". The percentage change calculator is specialised for before-and-after comparisons and signs the result so increases and decreases are obvious.
- Does this tool store my numbers?
- No. The calculator runs entirely in your browser and nothing you enter is sent to a server, logged, or saved between visits.
- Is the percentage change calculator free?
- Yes. It is free to use with no signup, no account, and no usage limit.