Everyday Calculators
Percentage Calculator
Updated Aug 21, 2026 Reviewed Aug 21, 2026
Calculate a percentage of a number, find one value as a percentage of another, measure percentage change, or adjust a value by a percentage.
Four percentage questions in one tool
Choose a relationship and enter the values
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Relationship preview
Compare the two values
Formula
result = value × percentage ÷ 100
- Percentage amount
- 50
- Absolute difference
- -150
- Direction
- Decrease
How to use this calculator
- 1Choose the percentage question that matches your task.
- 2Enter the values shown for that mode and choose the desired decimal places.
- 3Calculate the answer and review the substituted values and comparison.
Formula
Part = whole × percentage ÷ 100
A percentage is a ratio per hundred. Other modes rearrange this relationship or compare the difference with the original value.
Calculation steps
- Convert the entered percentage to a decimal by dividing by 100.
- Apply the mode-specific multiplication, division, or change formula.
- Keep full precision internally and format only the displayed result.
Worked example
Twenty-five percent of 200 is 50 because 200 × 25 ÷ 100 = 50.
Assumptions
- Percentage change uses the absolute value of the original as the denominator.
- An original or whole value of zero is rejected where division would be undefined.
- The decimal-place setting affects display only, not the internal calculation.
Sources
Frequently asked questions
Why is percentage change undefined from zero?
The standard formula divides the difference by the original value, so an original value of zero would require division by zero.
Can a percentage be above 100%?
Yes. A part can exceed the chosen whole, and a value can increase by more than its original amount.
How are negative changes shown?
A negative percentage change is labeled as a decrease; a positive result is an increase.
Does changing decimal places change the answer?
No. It changes only how many decimal places are displayed.