Percentage Calculator

Calculate percentages instantly. Find X% of Y, percentage change, add or subtract percentages — with formulas shown for every calculation.

What is X% of Y?

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How to Calculate Percentages

Percentages are everywhere — from shopping discounts and restaurant tips to financial reports and academic grades. Understanding how to calculate them quickly is an essential life skill.

Our free Percentage Calculator supports six different calculation modes, shows the mathematical formula for every result, and keeps a history of your calculations. No more mental math mistakes.

6 Ways to Calculate Percentages

X% of Y

Find a percentage of any number. Great for tips, discounts, and tax calculations.

X is ?% of Y

Find what percentage one number is of another. Useful for grades and ratios.

% Increase

Calculate the percentage increase between two values. Perfect for growth tracking.

% Decrease

Calculate the percentage decrease between two values. Track price drops and losses.

Add X%

Add a percentage to a number. Calculate prices with tax or markups.

Subtract X%

Subtract a percentage from a number. Calculate discounted prices instantly.

Percentage Formulas Reference

CalculationFormulaExample
X% of Y(X/100) × Y20% of 150 = 30
X is ?% of Y(X/Y) × 10045/200 × 100 = 22.5%
% Increase((New−Old)/Old) × 100(120−100)/100 = 20%
% Decrease((Old−New)/Old) × 100(100−80)/100 = 20%
Add X%Y + (X/100 × Y)100 + 8.25% = 108.25
Subtract X%Y − (X/100 × Y)100 − 30% = 70

Frequently Asked Questions

How do I find what percentage one number is of another?▼
Divide the part by the whole and multiply by 100. For example, 30 is what % of 200? → (30 ÷ 200) × 100 = 15%.
How do I calculate percentage increase?▼
Subtract the old value from the new value, divide by the old value, then multiply by 100. Example: 80 to 100 → ((100-80)/80) × 100 = 25% increase.
How do I calculate a discount?▼
Use 'Subtract X%' mode. 20% off $100 → $100 − (20% × $100) = $80.
What is reverse percentage?▼
It finds the original value before a percentage was applied. If a price after 20% tax is $120, the original was $120 / 1.20 = $100.
How to calculate sales tax?▼
Use 'Add X%' mode. Enter the tax rate and pre-tax amount. 8.25% tax on $75 → $75 + $6.19 = $81.19.
How to convert a fraction to a percentage?▼
Divide the top number by the bottom and multiply by 100. For example, 3/4 = 0.75 × 100 = 75%.
What is percentage change?▼
It measures how much a value changed relative to the original. Formula: ((New − Old) / |Old|) × 100. Positive = increase, negative = decrease.
How to calculate a tip?▼
Use 'X% of Y'. For a 15% tip on $50: 15% × $50 = $7.50.
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