Solve any percentage problem: find a percentage, calculate what percent one number is of another, compute percentage difference between two values, or apply a percentage increase or decrease.
How to use this calculator
Choose the calculation type you need. For the main calculator, leave one field empty and fill the other two, then click Calculate. For common phrases and change calculators, fill in all fields and click Calculate.
Provide any two values and click Calculate to find the third.
Frequently Asked Questions
Three common percentage expressions, each solved independently.
Calculate the percentage difference between two values.
Calculate the result of increasing or decreasing a value by a given percentage.
A percentage is a number or ratio expressed as a fraction of 100, denoted by the symbol "%". It is one of the most common ways to express proportional relationships in everyday life — from discounts and interest rates to statistics and test scores. The word "percent" comes from the Latin per centum, meaning "by the hundred."
The fundamental formula is P × V1 = V2, where P is the percentage (as a decimal), V1 is the base value, and V2 is the result. Given any two of these three values, the third can be calculated.
What is X% of Y? Multiply Y by X/100. For example, 15% of $80 = $80 × 0.15 = $12.
X is what % of Y? Divide X by Y and multiply by 100. For example, 12 is what % of 80? = (12/80) × 100 = 15%.
X is Y% of what? Divide X by (Y/100). For example, 12 is 15% of what? = 12 / 0.15 = 80.
Percentage change measures how much a value has changed relative to its original value: (New − Old) / Old × 100. It is directional — a positive result means an increase, and a negative result means a decrease. For example, a price rising from $50 to $65 is a 30% increase.
Percentage difference measures the relative difference between two values when there is no defined "original" value: |V1 − V2| / ((V1 + V2) / 2) × 100. It is symmetric and always positive. This is useful when comparing two independent measurements.
Percentages appear everywhere in daily life. In finance, interest rates, tax rates, and investment returns are all expressed as percentages. In retail, discounts and markups use percentage calculations. In health, body fat percentage and BMI classifications rely on percentages. Understanding how to calculate percentages accurately helps you make better financial decisions, interpret data correctly, and avoid common mathematical pitfalls.
→ To find X% of Y: multiply Y by X/100.
→ To find what % X is of Y: divide X by Y and multiply by 100.
→ Percentage difference is symmetric; percentage change is not.
→ A 50% increase followed by a 50% decrease does NOT return to the original value.