Calculadora de porcentajes
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The percent formulas behind each tab
Almost every percent question falls into one of four shapes. To find a portion, multiply: X% of Y = (X ÷ 100) × Y, so 15% of 200 is 0.15 × 200 = 30. To find what share one number is of another, divide: X ÷ Y × 100, so 30 out of 200 is 15%. To compare two values without picking a direction, the percentage difference divides their absolute difference by their average: |V1 − V2| ÷ ((V1 + V2) ÷ 2) × 100. And to grow or shrink a number by a set rate, multiply it by 1 plus or minus the rate: 200 increased by 10% is 200 × 1.10 = 220. Each tab above runs one of these formulas for you.
Difference versus change
Percentage difference treats both values symmetrically — the answer is the same whether you compare 10 to 20 or 20 to 10, because it divides by the average of the pair. Percent increase or decrease is directional: it applies a chosen rate to a starting number, so raising 200 by 10% gives 220 while lowering 200 by 10% gives 180. Pick the difference tab when neither value is the "original", and the change tab when one number is clearly the starting point.
Preguntas frecuentes
How do I convert a percent to a decimal?
Divide by 100, which is the same as moving the decimal point two places left: 15% becomes 0.15 and 0.5% becomes 0.005. The "X is what % of Y" tab shows the decimal form of its answer in the results.
Why is the percentage difference undefined in some cases?
The formula divides by the average of the two values. When the pair averages to zero — for example 10 and −10 — there is nothing to divide by, so no meaningful percentage difference exists.
Does the percent change tab sign the answer for me?
You choose Increase or Decrease and the tab applies that direction to the number you enter. The "Change amount" row shows how far the value moved, with a plus or minus sign so the shift is never ambiguous.