Percentage Calculator – Find %, Percent Change & More

Choose a Calculation

Pick the question you want answered, then fill in the blanks.

What is % of ?

Result

15% of 200 is 30

Formula: Result = Number × Percentage ÷ 100

How the Percentage Calculator Works

A percentage is a number expressed as a fraction of 100. This percentage calculator covers the three questions people ask most often, and each one has its own tab: what is X% of Y, X is what percent of Y, and percentage increase or decrease between two values. Results update as you type.

Percentage Formulas

Question	Formula	Example
What is X% of Y?	Y × X ÷ 100	15% of 200 = 200 × 15 ÷ 100 = 30
X is what % of Y?	X ÷ Y × 100	45 of 180 = 45 ÷ 180 × 100 = 25%
% change from A to B	(B − A) ÷ A × 100	80 → 100 = 20 ÷ 80 × 100 = +25%
Increase Y by X%	Y × (1 + X ÷ 100)	200 + 15% = 200 × 1.15 = 230
Decrease Y by X%	Y × (1 − X ÷ 100)	200 − 15% = 200 × 0.85 = 170

Percent change depends on the starting value. A rise from 100 to 125 is +25%, but falling back from 125 to 100 is only −20%, because the 25-point drop is measured against the larger starting number of 125.

Everyday Uses

🛍️ Shopping & Sales

Work out how much a 30% discount takes off. For the final price with tax, use the Discount Calculator.

📈 Growth & Change

Compare revenue, prices or test scores between two periods with the % change tab. For investment growth over many years, see the Interest Calculator.

🧾 Tax & Tips

Find a percentage of any bill. For dedicated tools, use the Tip Calculator or the VAT Calculator.

Frequently Asked Questions

How do you calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. Example: 15% of 200 = 200 × 15 ÷ 100 = 30. You can also convert the percentage to a decimal (15% = 0.15) and multiply: 200 × 0.15 = 30.

How do you find what percent one number is of another?

Divide the part by the whole and multiply by 100. Example: 45 is what percent of 180? 45 ÷ 180 = 0.25, and 0.25 × 100 = 25%.

How do you calculate percentage increase or decrease?

Subtract the old value from the new value, divide by the old value, and multiply by 100. Example: from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase. From 100 to 80 is (80 − 100) ÷ 100 × 100 = −20%, a 20% decrease.

Why is a 25% increase not reversed by a 25% decrease?

Because the base changes. 100 plus 25% is 125. A 25% decrease of 125 is 93.75, not 100. To get back from 125 to 100 you need a 20% decrease, since the drop of 25 is measured against the larger number 125.

What is the difference between percentage points and percent?

Percentage points describe the simple difference between two percentages, while percent change is relative. If an interest rate rises from 4% to 5%, it increased by 1 percentage point, which is a 25% relative increase (1 ÷ 4).

Percentage Calculator – Find %, Increase & Decrease