Calc4Living

Personal Finance & Budget · Free calculator

Percentage Calculator

Calculate a percentage of a number, a ratio as a percentage, or a signed percentage change.

Your inputs

Prefilled values are editable examples. Enter your own amounts. All fields are required unless marked optional. Results clear whenever an input or name changes.

Negative values are allowed. Changing the calculation keeps your two input numbers.

Finite positive, zero and negative values are allowed.

A zero denominator produces an undefined result rather than infinity.

Your calculation

Results

Review the assumptions, enter your values and calculate.

How do I calculate a percentage, ratio or percentage change?

X% of Y = (X/100) × Y. X as a percentage of Y = (X/Y) × 100. Percentage change = (new − original)/original × 100. Zero denominators produce an undefined result.

Worked example

25% of 200 is 50. 30 as a percentage of 120 is 25%. A change from 80 to 100 is a 25% increase; from 100 to 80 is a 20% decrease.

Assumptions & limitations

  • Negative values are allowed. With a positive original value, positive change means increase and negative change means decrease. With a negative original, this signed formula reverses that usual interpretation; compare the values as well as the sign.
  • A ratio with denominator zero or percentage change from zero is undefined, including 0/0. Zero percent of a finite number is zero. Calculations that cannot be represented finitely are rejected.
  • Percentages are dimensionless. Use consistent units for both values when calculating a ratio or change.