Everyday Math

Percentage Calculator

Calculate percentages instantly — percent of a number, percent change, and what percent X is of Y.

What is % of ?

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% change from to

How Percentage Calculations Work

A percentage is a way of expressing a fraction of 100. The word comes from the Latin per centum — "by the hundred." Percentages are one of the most widely used mathematical concepts in everyday life, appearing in everything from sales discounts to interest rates to election results.

The Three Most Common Percentage Calculations

Our calculator handles all three standard types:

  1. Finding X% of a number: "What is 20% of 500?" → 500 × 0.20 = 100
  2. Finding what percentage X is of Y: "75 is what percentage of 300?" → (75 ÷ 300) × 100 = 25%
  3. Percentage change (increase or decrease): "What is the % change from 80 to 100?" → ((100 − 80) ÷ 80) × 100 = +25%

Real-World Percentage Examples

  • Shopping discounts: A $120 jacket is 30% off → 30% of $120 = $36 off → You pay $84
  • Tax calculation: What is 8.5% sales tax on a $250 purchase? → $21.25
  • Grade calculation: You scored 43 out of 55 — what percentage is that? → 78.2%
  • Salary increase: You got a pay rise from $52,000 to $56,000 — what % increase? → 7.69%
  • Investment return: Stock went from $45 to $38.70 — what % loss? → −14%

How to Calculate Percentage Change

Percentage change is calculated as: ((New Value − Old Value) ÷ |Old Value|) × 100

A positive result is a percentage increase; a negative result is a percentage decrease. The absolute value of the old value is used in the denominator to handle cases where the starting value is negative.

Frequently Asked Questions

How do I calculate 15% of a number?
Multiply the number by 0.15. For example, 15% of 80 = 80 × 0.15 = 12. Alternatively, divide the number by 100 and multiply by 15.
What is the formula for percentage change?
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result means an increase; a negative result means a decrease.
How do I find what percentage one number is of another?
Divide the first number by the second number, then multiply by 100. Example: what percentage is 45 of 180? (45 ÷ 180) × 100 = 25%.
What is the difference between percentage and percentage points?
A percentage is relative to a base value (e.g., 10% of 200 = 20). A percentage point is an absolute difference between two percentages. If interest rates go from 3% to 5%, that is a 2 percentage point increase, but a 66.7% relative increase.
How do I add a percentage to a number?
To add X% to a number, multiply the number by (1 + X/100). For example, to add 20% to $50: $50 × 1.20 = $60. To subtract X%, multiply by (1 − X/100).