Percentage Calculator
Online percentage calculator covering the three common cases: what B% of A is, what percentage a part is of a total, and the percentage change between two values.
FreeOnline Tool
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How to Use
- What is B% of A: enter the value A and the percentage B to see the result update live.
- Part as a percentage of a total: enter the part and the total to see the percentage live.
- Percentage change: enter the starting and ending values to see the increase or decrease as a percentage, where positive means growth and negative means decline.
- The three calculators are independent and can be used at the same time. Click Load sample data to see all three worked through with examples.
Features
- Percentage of a value: enter A and B to work out what B% of A equals.
- Share calculation: enter a part and a total to get the part as a percentage of the total, with an error message when the total is zero.
- Percentage change: enter a starting and an ending value to get the change as a percentage, signed to show the direction, with an error message when the starting value is zero.
- All three calculators update instantly as you type, with no extra button to press.
Use Cases
Discounts and tax
Enter a list price and a discount percentage to work out the saving or the tax due in seconds.
Exam and performance scores
Enter a score and the maximum to get the score rate or completion rate as a percentage.
Salary and performance changes
Enter the amounts before and after a raise, or this period against last period, to get the percentage change.
Quick share checks in data analysis
While working through a report, confirm whether the share of a line item against the total is correct.
FAQ
What happens if I enter zero as the total in the share calculator?
A percentage cannot be calculated when the total is zero, since dividing by zero is meaningless, so the tool shows an error message rather than a bogus result.
What does the sign on a percentage change mean?
A positive result means the value rose from the start to the end, for example 100 to 120 shows +20.00%, while a negative result means it fell, for example 200 to 150 shows -25.00%.
What happens if the starting value of a percentage change is zero?
Percentage change cannot be calculated from a starting value of zero because the denominator would be zero, so the tool shows an error message.
Can I use all three calculators at once?
Yes, the three sections are independent and do not affect one another, so you can fill them all in and read all three results together.