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
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.
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