How to use
- Fill in two numbers in whichever calculation you need — results appear instantly.
- Percent change shows how much a value grew or shrank, e.g. prices, revenue or weight.
- The last row adds or subtracts a percentage — perfect for price increases and discounts.
Good to know
X% of Y = Y × X ÷ 100. X is what % of Y = X ÷ Y × 100.
Percent change = (new − old) ÷ old × 100. Note that a 50% drop followed by a 50% rise doesn’t get you back: 100 → 50 → 75.
A percentage point is the simple difference between two percentages. If a rate goes from 3% to 4%, it rose by 1 percentage point, or by 33%.
FAQ
How do I calculate a discount?
Price × (1 − discount ÷ 100). Use the last row: the "−" result is the sale price.
Is 30% off plus an extra 10% off the same as 40% off?
No — it’s 37% off, because the second discount applies to the already reduced price (1 − 0.7 × 0.9 = 0.37).
How do I reverse a percentage increase?
Divide by (1 + percent ÷ 100). For example, a price of 120 after a 20% increase was originally 120 ÷ 1.2 = 100.
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