Percentage Calculator
Solve common percentage math.
Calculate percentages and percentage change in one compact tool.
Percentage Inputs
Part divided by whole gives the percentage.
Percentage Summary
How It Works
Select Calculation Type
Choose between 'X is what % of Y', 'X% of Y', or 'Percentage Increase/Decrease'.
Enter Numbers
Enter the required numeric values into the input fields.
Click Calculate
Get your result instantly along with a breakdown of the math.
Switch Variants
Try different variants of the same numbers to solve different parts of the problem.
Percentage Calculator Overview
A general-purpose Percentage Calculator handles the most common percentage problems people run into — finding what percentage one number is of another, finding a percentage of a number, and calculating percentage increase or decrease between two values.
Why Use This Calculator
- Handles multiple percentage calculation types in one tool
- Great for shopping discounts, grades, and financial math
- Instant, accurate results with no manual formulas
- Works for both increases and decreases
Common Formulas
Ratio: (X ÷ Y) × 100
Value: (X ÷ 100) × Y
Change: [(New − Old) ÷ Old] × 100
Worked example: increase and reverse percentage
A fee rises from 1,200 to 1,380, and you want the percentage increase. Later, you see a discounted price of 920 after 20% off.
- 1Increase amount: 1,380 - 1,200 = 180.
- 2Percentage increase: 180 / 1,200 x 100 = 15%.
- 3Reverse discount original: 920 / (1 - 0.20) = 1,150.
- 4The original price before discount was 1,150.
The same calculator handles different percent relationships, but the inputs mean different things depending on the selected mode.
How this differs from marks percentage
Use this page for general math, finance, discounts, and percent change. Use marks percentage when your inputs are obtained marks and total exam marks.
Common mistakes to avoid
- Do not confuse percentage points with percent change.
- Do not divide by the new value when calculating percent increase from an old value.
- Do not use reverse percentage mode when you simply need X% of a number.
Content author
Abubakar
Calculator Content Author & Full Stack Developer
Writes and reviews the formulas, examples, FAQs, and accuracy notes used across Grade Average Calculator tools.
Frequently Asked Questions
What's the difference between percentage increase and percentage points?
A percentage increase is relative (e.g., going from 10% to 15% is a 50% increase), while a percentage point difference is absolute (a 5 percentage point increase). These are commonly confused.
Can percentage be negative?
Yes — a negative result in a percentage change calculation indicates a decrease rather than an increase.
How do I calculate a percentage discount?
Use 'What is X% of Y' to find the discount amount, then subtract it from the original price, or use the increase/decrease formula with the discounted price as the 'new value.'
Why do my manual calculations sometimes differ slightly from the tool?
Usually due to rounding — try carrying more decimal places in manual calculations for an exact match.
How do I calculate a reverse percentage, like finding the original price before a discount?
Divide the discounted price by (1 − discount rate as a decimal). For example, if $76 is the price after a 5% discount, the original price = 76 ÷ 0.95 = $80.
What is percentage error and how is it calculated?
Percentage error measures how far an estimated or measured value is from the true value: [(|Estimated − Actual|) ÷ Actual] × 100. It's commonly used in science and engineering to express measurement accuracy.
How do I convert a fraction to a percentage?
Divide the numerator by the denominator, then multiply by 100. For example, 3/4 = 0.75, and 0.75 × 100 = 75%.
What is the difference between 10% and 10 percentage points?
10% is relative to a base value. 10 percentage points is an absolute movement, such as 60% to 70%.
Can this calculate discounts?
Yes. Use percentage-of for the discount amount or reverse percentage to recover the original price.
Why does percent change use the old value as the base?
Because the change is measured relative to where the value started.