CalcPick

Percentage Calculator

Three percentage modes in one calculator: find a percentage of a number, work out what percentage one value is of another, or measure increase and decrease between two values.

What is X% of Y?

%
Result
30
15% of 200 = 30

How Percentage Calculations Work

A percentage is a way of expressing a number as a fraction of 100. The word percent literally means "per hundred." Most everyday percentage problems fall into one of three categories, and this calculator covers all three.

1. Finding a Percentage of a Number

When you want to find a portion — like 15% of a $200 bill, 8% sales tax on a $35 purchase, or a 5% raise on your salary — multiply the number by the percentage and divide by 100. The formula is result = (number × percent) / 100. Quick mental trick: 10% is just the number with the decimal moved one place left.

2. Working Out What Percentage One Number Is of Another

Use this when you have a part and a whole and want to know the ratio as a percentage. Test score 47 out of 50? Sales of $1,250 against a $5,000 quota? The formula is percent = (part / whole) × 100. The answer can be greater than 100% if the part is larger than the whole.

3. Percentage Change Between Two Values

Percentage change measures how much something has grown or shrunk relative to the starting value. The formula is percent change = ((new − old) / old) × 100. A positive result is an increase, a negative result is a decrease. Used for stock returns, year-over-year growth, price markdowns, and inflation.

Common Real-World Uses

  • Tax and tip: Find the dollar amount of a percentage applied to a bill.
  • Discounts and sales: Calculate the final price after a percentage off (see also the Discount Calculator).
  • Grades and scores: Convert raw scores into percentage grades.
  • Growth and decline: Compare two periods to see year-over-year, quarter-over-quarter, or week-over-week change.
  • Investing: Compute returns as a percent of the original investment.

Frequently Asked Questions

How do I calculate a percentage of a number?

Multiply the number by the percentage, then divide by 100. For example, 15% of 200 is (200 × 15) / 100 = 30. This calculator does it automatically — just enter the percentage and the number.

How do I find what percentage one number is of another?

Divide the part by the whole, then multiply by 100. For example, if 25 is part of 200, the percentage is (25 / 200) × 100 = 12.5%. Use the "X is what % of Y?" mode for this.

How do I calculate percentage increase or decrease?

Subtract the original value from the new value, divide by the original, then multiply by 100. For example, from 80 to 100: (100 − 80) / 80 × 100 = 25% increase. A negative result means a decrease.

What is the difference between percentage points and percent?

A percentage point is an absolute difference between two percentages, while a percent is relative. If a rate goes from 10% to 15%, that is a 5 percentage point increase, but a 50% relative increase. This calculator returns relative percent change.