What formulas are used?

X% of Y = (X × Y) / 100. X is what % of Y = (X / Y) × 100. Percent change from X to Y = ((Y − X) / X) × 100.

How do I calculate a discount?

Use mode 1 (X% of Y). If an item costs $80 with 25% off, enter 25% of 80 = $20 discount. Final price: $80 − $20 = $60.

If change is positive, it's an increase. Negative means decrease. The tool shows the sign automatically in mode 3.

Not in this tool. For compound interest use the loan calculator. For multi-step percentage changes, chain two operations manually.

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What formulas are used?: X% of Y = (X × Y) / 100. X is what % of Y = (X / Y) × 100. Percent change from X to Y = ((Y − X) / X) × 100.
How do I calculate a discount?: Use mode 1 (X% of Y). If an item costs $80 with 25% off, enter 25% of 80 = $20 discount. Final price: $80 − $20 = $60.
What is percentage increase vs decrease?: If change is positive, it's an increase. Negative means decrease. The tool shows the sign automatically in mode 3.
Can I calculate compound percentages?: Not in this tool. For compound interest use the loan calculator. For multi-step percentage changes, chain two operations manually.