How to use the Percentage Calculator
- 1 Pick the line that matches your question. Each line is a separate calculator.
- 2 Type your two numbers into the boxes. Decimals and negative numbers are fine.
- 3 Read the answer as you type. There is no button to press.
- 4 Check the formula next to the answer if you need to show your working or repeat the calculation by hand.
Features
Three calculators in one
Percent of a number, percent one value is of another, and percent increase or decrease cover nearly every percentage problem in shopping, school and business.
Shows the formula
Every result comes with the exact calculation, which is useful for homework, exams and double-checking spreadsheets.
Handles edge cases
Dividing by zero is caught and explained instead of returning a meaningless number. Percentage change uses the absolute starting value, so changes from negative numbers are reported correctly.
Precise results
Answers are rounded only for display, up to six decimal places, so small percentages and large amounts both stay accurate.
When to use it
Discounts and sale prices
To find a 25% discount on 3,200, enter 25 and 3,200 in the first line to get 800, then subtract it from the price. The result is a sale price of 2,400.
Exam marks and scores
Scored 412 out of 550? Enter them in the second line to get 74.91%. This is the number most admission forms ask for.
Salary, price and growth changes
If rent went from 40,000 to 46,000, the third line shows a 15% increase. Use it for price rises, sales growth or weight change.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 240 is 15 ÷ 100 × 240 = 36.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 36 is 36 ÷ 240 × 100 = 15% of 240.
How is percentage increase or decrease calculated?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = a 25% increase.
Why isn't a 50% rise followed by a 50% fall back to the start?
Because the second percentage applies to a different base. 100 rises 50% to 150, and a 50% fall from 150 is 75, not 100.
What is the difference between percent and percentage points?
If an interest rate moves from 10% to 12%, it rose by 2 percentage points, but by 20 percent relative to where it started.
Reviewed by ToolsUnlocked Team · Last updated