Percentage Calculator

What Is a Percentage Calculator?

A percentage calculator handles the three most common percentage problems: finding a percentage of a number, finding what percentage one number is of another, and finding the percentage change between two values.

How to Use the Percentage Calculator

Choose the type of percentage calculation you need.
Enter the required values.
Your result updates instantly.

Percentage Formulas

X% of Y

Result = (X ÷ 100) × Y

X is what % of Y

Percentage = (X ÷ Y) × 100

Percentage Change

% Change = ((New − Old) ÷ Old) × 100

Worked Examples

Example 1: 25% of 200

Result = (25 ÷ 100) × 200 = 50

Example 2: 50 is what % of 200?

Percentage = (50 ÷ 200) × 100 = 25%

Example 3: Change from 80 to 100

% Change = ((100 − 80) ÷ 80) × 100 = 25% increase

Understanding Your Results

A positive percentage change means an increase; a negative percentage change means a decrease. Percentage change is relative to the original (starting) value, which is why the order of the two numbers matters.

Common Uses for Percentage Calculations

Calculating discounts, sales tax, or tips.
Working out grades or test scores.
Tracking growth or decline in sales, weight, or investments.
Comparing survey results or statistics.

Common Mistakes to Avoid

Confusing "percentage of" with "percentage change" — they answer different questions.
Using the wrong base number when calculating percentage change (always divide by the original value).
Forgetting that a percentage decrease of X% followed by an increase of X% doesn't return you to the original number.

Frequently Asked Questions

How do I calculate a percentage of a number? ▼

Divide the percentage by 100, then multiply by the number. For example, 25% of 200 is (25÷100)×200 = 50.

How do I find what percentage one number is of another? ▼

Divide the first number by the second, then multiply by 100. For example, 50 is (50÷200)×100 = 25% of 200.

How do I calculate percentage increase or decrease? ▼

Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is an increase; a negative result is a decrease.

Why isn't a 20% decrease then a 20% increase back to the original number? ▼

Because each percentage is calculated on a different base value — the increase is calculated on the smaller, already-decreased number, so it doesn't fully offset the earlier decrease.

What's the difference between percentage points and percentage change? ▼

Percentage points measure the raw difference between two percentages (e.g., 40% to 50% is a 10 percentage point increase), while percentage change measures relative change (a 25% increase in this case).