Percentage Increase & Decrease Calculator
Enter the starting number and the final number below to see the percentage increase or decrease. This calculator is useful for comparing price changes, growth figures or reductions over time.
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How the Percentage Increase & Decrease Calculator Works
The calculation uses:
Understanding Percentage Increase and Decrease
For example, percentage change is commonly used to:
If a supplier charged you £40 for materials last year, but the new price is £48, you need to know the percentage increase to adjust your own pricing.
– Original Value: 40
– New Value: 48
The calculator finds the difference (£8) and divides it by the original (£40) to show a 20% increase. You now know your costs have risen by 20%.
Example 2: Calculating a Performance Drop (Website Traffic)
If your website had 5,000 visitors in January but dropped to 4,250 visitors in February, you can measure the decline.
– Original Value: 5,000
– New Value: 4,250
The calculator determines the difference (750 visitors) and divides it by the original figure (5,000) to reveal a 15% decrease in traffic.
When Should You Use This Calculator?
About This Percentage Change Calculator
While useful for comparison and learning, this calculator does not replace professional analysis or advice.
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Frequently Asked Questions
Percentage increase is calculated by dividing the difference between the new value and the original value by the original value, then multiplying by 100.
Percentage decrease uses the same formula but applies when the new value is lower than the original value.
Yes, and this is a common mix-up. A percentage increase/decrease calculator measures the journey from a specific starting point (e.g., last year’s sales vs this year’s sales). A percentage difference calculator compares two values where neither is necessarily the starting point (e.g., comparing the height of two different buildings), by finding the percentage difference relative to their average.
Mathematically, you cannot calculate a percentage increase from an original value of zero, because it involves dividing by zero. If you went from 0 sales to 10 sales, it is simply an absolute gain of 10, not a percentage increase.
Yes. It can be used for price increases, discounts, inflation changes or any value comparison.
Disclaimer
Last checked/updated March 2026.