20% of 85 = 17.
Keeping track · Calculate · Browser-local
Percentage Calculator
Work out a percentage, compare two values, or see how much something changed without mental gymnastics.
Quick percentage math
Ask the question the way you mean it.
Choose one of the three common percentage questions, enter your values, and get a clear answer right here.
A useful caveat
Percent change uses the starting value as its baseline.
A change from zero is not defined as a percentage. When a result cannot fit cleanly in ten significant digits, it is marked approximate rather than pretending to be more precise than the calculation.
A couple of useful details
Three percentage questions, one place.
Find a percent of a number, compare two numbers, or see how much something changed. Enter the numbers you have; the calculator shows the formula alongside the answer.
Percent change uses the starting value as its baseline, so a change from zero is not defined. Results that cannot fit cleanly in ten significant digits are marked approximate.
Subtract the original value from the new value, divide by the original value, then multiply by 100. The calculator shows the calculation detail for the values you enter.