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% Percentage Calculator

Calculate any percentage instantly — find what X% of Y is, what percentage X is of Y, percentage change, or add/subtract a percent from any number.

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How to Calculate a Percentage

A percentage is a number expressed as a fraction of 100. "Per cent" literally means "per hundred." Percentage calculations are used in discounts, tips, taxes, interest rates, grades, statistics, and everyday financial decisions.

The four most common percentage calculations — all handled by this calculator — are: finding a percentage of a number (what is 15% of 200?), finding what percentage one number is of another (30 is what percent of 200?), percentage change (from 80 to 100 is what percent increase?), and adding or subtracting a percentage from a number (100 plus 20% = 120).

Percentage Change Formula

Percentage change = ((New − Old) ÷ Old) × 100. A positive result is an increase; negative is a decrease. This formula is used for price changes, salary increases, population growth, and any "how much did it change" question. Example: a price rises from $80 to $100 — percentage change = ((100−80)÷80) × 100 = 25% increase.

Common Percentage Shortcuts

To find 10% of any number: move the decimal point one place left. 10% of 350 = 35. For 5%, halve the 10% result: 5% of 350 = 17.5. For 20%, double the 10% result: 20% of 350 = 70. For 1%, move the decimal two places left: 1% of 350 = 3.5. These shortcuts let you estimate percentages mentally in seconds.

Frequently Asked Questions

How do I calculate 15% of a number? +
Multiply the number by 0.15. Example: 15% of 240 = 240 × 0.15 = 36. Shortcut: find 10% (move decimal left), then add half of that for 5%. 10% of 240 = 24, 5% = 12, total 15% = 36.
How do I calculate a tip percentage? +
Multiply the bill by the tip percentage as a decimal. For 20% tip on a $75 bill: 75 × 0.20 = $15 tip, total = $90. Shortcut: move the decimal (10% = $7.50), double it for 20% = $15. For 18%: 10% + 8% = $7.50 + $6 = $13.50.
How do I calculate a percentage increase? +
Formula: ((New Value − Old Value) ÷ Old Value) × 100. If your salary goes from $50,000 to $55,000: ((55,000 − 50,000) ÷ 50,000) × 100 = (5,000 ÷ 50,000) × 100 = 10% increase.
What is the difference between percentage and percentage points? +
Percentage points measure absolute difference between two percentages. If interest rates go from 3% to 5%, that is a 2 percentage point increase — but a 67% relative increase. Confusing the two is a common error in reporting. "The unemployment rate fell 2 percentage points" means from e.g. 7% to 5%, not that it fell by 2% of 7%.

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