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Percentage Change Calculator

Calculate the percentage increase or decrease between two values. Features natural language explanations and handles negative numbers correctly.

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Category Math & Algebra
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About

Calculating the percentage difference between two numbers is a fundamental requirement in finance, statistics, and daily life. Whether measuring stock portfolio performance, analyzing profit margins, or comparing year-over-year revenue, the directionality (increase vs. decrease) and magnitude are critical.

This tool specifically handles edge cases that confuse standard calculators, such as negative starting values (e.g., calculating debt reduction) or zero values. It provides a natural language summary to remove ambiguity, clearly stating whether the change represents a gain, a loss, or a shift in magnitude.

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Formulas

The standard formula for percentage change divides the difference by the absolute value of the starting number. This ensures directionality remains correct even when the starting value is negative.

%Δ = V2 − V1|V1| × 100

Reference Data

ScenarioStart Value (V1)End Value (V2)CalculationResult
Price Hike100150(50 / 100) * 100+ 50%
Discount5030(-20 / 50) * 100− 40%
Debt Reduction−100−50(50 / |-100|) * 100+ 50%
Zero Start0100UndefinedError
To Zero1000(-100 / 100) * 100− 100%

Frequently Asked Questions

Yes. If a value doubles, the increase is 100%. If it triples, the increase is 200%. There is no upper limit to percentage increase.
Generally, no, if the lowest possible value is zero (like a stock price). Losing all value is a 100% decrease. However, in contexts like profit turning into debt, you can mathematically have a decrease exceeding 100%.
Mathematically, calculating percentage change from zero is undefined because you cannot divide by zero. In practical terms, moving from 0 to 100 is often described as an "infinite" increase or simply stated as "New Position: 100".