Three different questions
15% of 200 is 30: multiply 200 by 15 and divide by 100. If 30 is part of 200, it represents 15%: divide 30 by 200 and multiply by 100.
The change from 80 to 100 is 25%: subtract 80 from 100, divide by the initial value 80 and multiply by 100. The denominator explains why returning from 100 to 80 is a 20% decrease, not 25%.
Zeros and negative numbers
A proportion with a zero denominator is undefined. Ordinary percentage change from an initial value of zero is also undefined.
With negative initial values, the signed formula may seem unintuitive. Interpret it in context rather than automatically describing it as financial growth.
- Choose the operation answering your question.
- Enter quantities and percentages with their signs.
- Calculate and check the denominator and units.
- Copy the result without confusing percentages with percentage points.
Percentages and percentage points
Going from 10% to 15% adds 5 percentage points but represents a relative increase of 50%. These figures describe different things.
Decimal results may be rounded for display. Do not imply more precision than your source data supports; this calculator does not replace financial or tax decisions.