Percentage Calculator

How to use this percentage calculator

A percentage calculator helps you calculate percentage relationships quickly without manual algebra. Whether you need to find percentage of a number (for discounts, tips, or VAT-style thinking), work out a percentage increase calculator or percentage decrease calculator scenario from an “old” to a “new” value, or compare two figures with a percentage difference calculator, each mode above maps to a common real-world question.

What is X% of Y?

Multiply Y by X and divide by 100: (X ÷ 100) × Y. Example: 20% of 150 is 30. This is the fastest way to answer “how much is this percent of that total?”.

X is what percent of Y?

Divide X by Y and multiply by 100: (X ÷ Y) × 100 (when Y is not zero). Example: 45 is 25% of 180. Use this when you know a part and a whole and want the share as a percent.

Percentage increase or decrease

From an original value A to a new value B: ((B − A) ÷ A) × 100 when A ≠ 0. A positive result is an increase; negative is a decrease. This is the standard percent change formula used in finance, retail, and analytics.

Add or subtract a percentage

To add a percentage, scale the number by 1 + (p ÷ 100). To subtract a percentage, use 1 − (p ÷ 100). Example: 200 + 15% = 230; 200 − 15% = 170.

Percentage difference between two numbers

When people ask for the percentage difference between two values, they often want a measure that does not favour the first or second number. Our tool reports the symmetric difference relative to the average magnitude of the two values, and also shows the simple absolute gap |A − B|.

• Five modes: percent of, is what % of, change, add/subtract %, and difference
• Works entirely in your browser — ideal for quick checks and homework
• Clear labels and formulas so you can trust and learn the math
• Free to use on BlueOrbit — no account required