Percentage Calculator
Find percentages, percentage change, and increases or decreases in seconds with clear formula breakdowns.
What is X% of Y?
Results update instantly. Switch modes to compare percentage calculations.
20% of 80 = 16
result = (20 ÷ 100) × 80
What is Percentage Calculator?
A percentage expresses a number as a fraction of 100. It is one of the most common ways to describe proportions, discounts, changes, and rates in everyday life — from sale prices and taxes to test scores and growth rates. This calculator handles the four most-used percentage calculations with clear formula explanations.
How to use it
- Pick the tab that matches your question (percent of, percent of total, change, or increase/decrease).
- Enter the two numbers the calculator asks for.
- Read the result and the formula used to reach it.
- Switch tabs or adjust inputs to compare calculations side by side.
Percentage formulas
Percent of a number: result = (percent ÷ 100) × number. Percent of total: percent = (part ÷ whole) × 100. Percentage change: ((new − old) ÷ old) × 100. Increase/decrease: result = number × (1 ± percent ÷ 100).
Frequently asked questions
Divide the percentage by 100, then multiply by the number. For example, 20% of 80 = (20 ÷ 100) × 80 = 16. This calculator applies the formula automatically.
Percentage change measures movement from an original value to a new one, so order matters: ((new − old) ÷ old) × 100. Percentage difference compares two values without a clear starting point, dividing by their average.
Use the 'increase or decrease by a percent' tab with a negative value, or multiply the price by (1 − discount ÷ 100). A $50 item at 30% off costs $50 × 0.70 = $35.
A negative percentage change means the value decreased. A positive number means it increased. The sign tells you the direction of the change.
Percentage change is undefined when the original value is zero, because you cannot divide by zero. In that case this calculator shows no result rather than an incorrect value.
Divide the numerator by the denominator, then multiply by 100. For example, 3 ÷ 4 = 0.75, which is 75%.
Related calculators
BMI Calculator
Check your body mass index with metric or imperial units and see where you land on the healthy range.
EverydayAge Calculator
Calculate your exact age in years, months, and days, plus a countdown to your next birthday.
FinancialLoan Calculator
Estimate monthly payments, total interest, and view a full amortization schedule for your loan.
FinancialCompound Interest Calculator
Watch your money grow. See how compound interest, contributions, and time work together.