Percentage Change Calculator
Calculate percentage increase or decrease between two values. Also computes percentage difference and what value X% of a number is.
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How to use this calculator
Subtract old from new, divide by the absolute old value, multiply by 100.
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Enter the original (old) value.
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Enter the new value.
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The calculator shows the percentage increase or decrease.
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Percentage difference is symmetric — it compares two values without a reference direction.
Frequently asked questions
What is the difference between percentage change and percentage difference?
Percentage change is directional: (new − old)/old × 100. It has a reference point (old value). Percentage difference is symmetric: |a − b| / ((a+b)/2) × 100. Use percentage change when comparing to a baseline; use percentage difference when neither value is more "original."
How do I calculate a 30% increase from a number?
Multiply by 1.30. A 30% increase on $80 = $80 × 1.30 = $104. For a 30% decrease: multiply by 0.70. For any percentage: multiply by (1 + %/100).
Why is a 50% loss not recovered by a 50% gain?
Start at $100. Lose 50%: $50. Gain 50% on $50: $75 — you are still down 25%. To recover from a 50% loss, you need a 100% gain. To recover from a 10% loss, you need an 11.1% gain. This asymmetry is why limiting losses is more important than maximising gains.
What is CAGR vs simple percentage change?
Simple percentage change measures total change over any period. CAGR (Compound Annual Growth Rate) normalises by the number of years to give an annualised rate. A 60% total change over 5 years is CAGR = (1.60)^(1/5) − 1 ≈ 9.86% per year.
Percentage change and percentage difference
How to use the percentage change
Use this percentage change to percentage increase or decrease between two values. Enter your values above and get your result in seconds. The tool is free, works on all devices, and keeps your data private — nothing is stored or shared.
How the percentage change works
The percentage change calculator uses standard formulas used in mathematics, science, and engineering. Enter your inputs, and the tool calculates the result instantly in your browser. No server-side processing means your data stays on your device. Results update in real time as you change inputs.
Percentage increase vs percentage decrease
Both use the same formula. From 80 to 100: (100−80)/80 = 25% increase. From 100 to 80: (80−100)/100 = −20% decrease. Note that a 25% gain is not reversed by a 25% loss — you need to apply each percentage to the current (different) value.
When to use percentage difference
Percentage difference is used when comparing two measurements where neither is the "correct" or "original" reference. Comparing two prices, two experimental measurements, or two survey results — use percentage difference. Comparing a price now to a price last year — use percentage change.
Percentage change in finance
Stock returns, index performance, GDP growth, and inflation rates are all expressed as percentage changes. "The S&P 500 returned 26% in 2023" means (end price − start price) / start price × 100 = 26. Annual percentage change is the most common benchmark for investment performance.
Percentage change: how it works
Built on well-established mathematical principles, this tool delivers accurate results for students, researchers, and professionals. Enter your values and get instant clarity without specialist software or manual arithmetic.
Who uses this tool?
Teachers, students, engineers, and data analysts use it to verify calculations, check homework, and solve problems faster. It is intuitive enough for beginners while comprehensive enough for professional use.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →