The three classic percentage problems solved instantly: X% of Y, X is what % of Y, and % change.
Percentages express a part of a whole in hundredths, and almost every everyday percentage question is one of three shapes. "How much is 15% of 240?" multiplies the whole by the rate. "36 is what percent of 240?" divides the part by the whole. "From 240 to 276, what changed?" divides the difference by the starting value. This calculator solves all three, always showing which operation was applied.
The most common trap is percentage change with a negative direction: a price that rises 50% and then falls 50% does not return to where it started — it ends 25% lower, because the second percentage applies to a bigger base. Seeing the explicit calculation next to the result helps avoid exactly this kind of slip.
All the math runs in your browser as you type, with no rounding surprises: results are shown with up to two decimal places, and the full-precision value is used internally.
X% of Y = Y × (X ÷ 100) · X as % of Y = (X ÷ Y) × 100 · Change from A to B = ((B − A) ÷ A) × 100
Use "X% of Y" to get the discount amount, then subtract it from the price. A 20% discount on R$ 150 is R$ 30, so you pay R$ 120.
Going from 10% to 15% is a rise of 5 percentage points, but a 50% increase relative to the starting rate. The calculator returns the relative change.
Because each percentage applies to a different base. 100 → 150 (+50%) → 75 (−50% of 150). The result is 25% below the start.
Yes — both comma and dot are accepted as decimal separators.
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Vai.la is not responsible for how the tools are used or for decisions made based on their results.