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Percentage Calculator

Three calculation modes — choose the one that fits your question.

AD SLOT 1 — Above Calculator

What is X% of Y?

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

What is
%
of
?
Answer
30
15% × 200 = 30
AD SLOT 2 — Below Calculator / Above FAQ

Frequently Asked Questions

How do I calculate what percentage X is of Y?
To find what percentage X is of Y, divide X by Y and multiply by 100. The formula is: (X ÷ Y) × 100 = percentage. For example, if you scored 42 out of 50 on a test, your percentage score is (42 ÷ 50) × 100 = 84%. This is the most common percentage calculation used in grading, budgeting, and data analysis.
What is the formula for percentage change?
Percentage change measures how much a value increased or decreased relative to the original value. Formula: ((New Value − Old Value) ÷ Old Value) × 100. A positive result means an increase; a negative result means a decrease. For example, if a stock went from $50 to $65, the percentage change is ((65 − 50) ÷ 50) × 100 = 30% increase. If it went from $50 to $40, the change is −20%.
How do I find a percentage of a number?
To find X% of Y, multiply Y by X and divide by 100. Alternatively, convert the percentage to a decimal (divide by 100) and multiply: Y × (X/100). For example, 15% of $80 = 80 × 0.15 = $12. This calculation is used daily for tips, discounts, tax calculations, and more.
What is the difference between percentage and percentage points?
Percentage is a relative measure (a proportion of some base value), while a percentage point is an absolute difference between two percentage values. For example, if an interest rate rises from 3% to 5%, it increased by 2 percentage points, but the percentage increase in the rate itself is ((5−3)/3) × 100 = 66.7%. This distinction is important in finance, polling data, and statistics. Confusing the two is a common error in media reporting.
How do I calculate a discount percentage?
To find the discount percentage, subtract the sale price from the original price, divide by the original price, then multiply by 100. Formula: ((Original Price − Sale Price) ÷ Original Price) × 100. For example, if a $120 item is on sale for $90: ((120 − 90) ÷ 120) × 100 = 25% discount. To find the sale price given a discount: Sale Price = Original Price × (1 − Discount%/100).
How do I calculate a tip percentage?
To calculate a tip, multiply the bill amount by the tip percentage divided by 100. For a 20% tip on a $45 bill: $45 × 0.20 = $9 tip, making the total $54. A simple mental math trick for 20%: move the decimal left one place to get 10% ($4.50), then double it for 20% ($9.00). For 15%: take 10% ($4.50) and add half of that ($2.25) to get $6.75.
What is a percentage increase calculator?
A percentage increase calculator computes how much a value has grown as a percentage of its starting value. This is the same as the percentage change formula when the new value is larger than the old value. It's used in business to measure revenue growth, in science to measure experimental results, and in personal finance to track investment returns or salary raises.
How do I reverse-calculate a percentage (find the original value)?
If you know the final value and the percentage applied, you can find the original value by dividing the final value by (1 + percentage/100) for an increase, or (1 − percentage/100) for a decrease. For example, if a price after a 25% increase is $125: original = $125 ÷ 1.25 = $100. If a $90 price represents a 10% discount: original = $90 ÷ 0.90 = $100.
AD SLOT 3 — Below FAQ

How to Use This Percentage Calculator

Switch between the three tabs to select the type of percentage problem you need to solve. The "X% of Y" tab finds an amount—useful for calculating tips on restaurant bills, figuring out sales tax, or determining how much a 20% discount saves you. The "X is what % of Y" tab works backwards, telling you the proportion—perfect for grade calculations or measuring what fraction of a budget something represents.

The "% Change" tab measures growth or decline between two values. This is the calculation behind stock price changes, year-over-year revenue comparisons, and salary increase negotiations. A positive result means the value went up; a negative result means it went down. All three modes update instantly as you type, so you can experiment with different numbers to see how percentages work in real-time.