Percentage Change Calculator
Compute the percent increase or decrease between any two numbers. Useful for stock prices, salaries, metrics, and comparing year-over-year figures.
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How this works
% Change = ((New − Old) ÷ |Old|) × 100Subtract the old value from the new value, divide by the absolute value of the original, then multiply by 100. A positive result is an increase; negative is a decrease. The absolute-value bars handle cases where the original value is negative.
Examples
Stock price rise
A stock goes from $80 to $100. Change = (100 − 80) ÷ 80 = 0.25 = 25% increase. The base for the percentage is always the original (older) value.
Price drop
A price falls from $100 to $80. Change = (80 − 100) ÷ 100 = −0.20 = 20% decrease. Note the asymmetry: +25% up, then −20% down does NOT bring you back to the start. A 25% rise followed by a 20% fall puts you back at the original because the base shifted.
Salary increase
Your salary goes from $65,000 to $72,800. Change = (72,800 − 65,000) ÷ 65,000 = 0.12 = 12% raise. A 12% raise is meaningfully above typical cost-of-living adjustments (2–4%).
Year-over-year metrics
Last year your site had 4,200 monthly visitors; this year it has 18,500. Change = (18,500 − 4,200) ÷ 4,200 = 3.405 = 340.5% increase. When growth is over 100%, it is often clearer to describe it as a multiple — "4.4× growth" reads better than "340%".
Common questions
Because the base changes. Going from 100 to 150 is a 50% increase (the base is 100). Going from 150 back to 100 is a 33.3% decrease (the base is now 150, and the change of 50 is smaller relative to 150). A 50% increase followed by a 33.3% decrease returns you to the start, not a 50% increase and a 50% decrease.
Percentage change from zero is mathematically undefined — you cannot divide by zero. The calculator returns N/A. In practice, when the original value is zero and the new value is positive, people sometimes describe it as "infinite growth" or just report the absolute change instead.
No. Percentage change has a clear direction — from old to new — and uses the old value as the base. Percent difference treats both values as equivalent and uses their average as the base: |A − B| ÷ ((A + B) ÷ 2) × 100. Percent difference is common in scientific measurement comparisons; percentage change is what you want for growth, returns, and before/after.
Multiply the growth factors. A 10% increase is a factor of 1.10. Three consecutive 10% annual increases give 1.10³ = 1.331, or 33.1% total growth over three years — not 30%. This is why compound interest grows faster than simple interest over time.
Yes, when the new value is more than double the old. Going from 50 to 200 is ((200 − 50) ÷ 50) × 100 = 300%. For very large changes, reporting as a multiplier (4×) is often more intuitive than a percentage (300%).
No. All calculations are done in your browser. Nothing you type is sent to a server. Your calculation history is stored locally and can be cleared any time.