What is the formula to calculate percentage?

The basic percentage formula is: (Part / Whole) × 100 = Percentage. For example, if you have 30 apples out of 200 total fruits, the percentage of apples is (30 / 200) × 100 = 15%.

How do you calculate percentage increase or decrease?

Percentage increase = [(New Value - Original Value) / Original Value] × 100. Percentage decrease = [(Original Value - New Value) / Original Value] × 100. For instance, if a product price rises from $50 to $60, the increase is [(60-50)/50]×100 = 20%.

How to calculate percentage of a number?

To find X% of a number Y, multiply Y by (X/100). For example, 20% of 150 is 150 × (20/100) = 30. You can also use our percentage calculator above for instant results.

What is the difference between percentage and percent?

Percentage is a noun representing a proportion out of 100, while percent is an adverb meaning 'per hundred' (symbol %). In practice, they are often used interchangeably. For example, 'the percentage is 25%' or '25 percent'.

How To Calculate Percentage

A complete step-by-step guide to understanding and calculating percentages. Use the interactive calculator below for instant percentage calculations and real-world examples.

By Jordan Rivera|Updated Mar 15, 2026

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Percentage (%)

Step-by-Step Percentage Calculation Guide

Calculating percentages involves simple formulas that can be applied in various situations. Here are the main methods:

Percentage of a Number: To find X% of Y, multiply Y by X/100. Example: 25% of 200 = 200 × (25/100) = 50.
Percentage Increase: To increase a number by X%, multiply by (1 + X/100). Example: Increase 200 by 25% = 200 × (1 + 25/100) = 250.
Percentage Decrease: To decrease a number by X%, multiply by (1 - X/100). Example: Decrease 200 by 25% = 200 × (1 - 25/100) = 150.
Percentage Change: To find what percentage X is of Y, divide X by Y and multiply by 100. Example: 50 is what % of 200? (50/200) × 100 = 25%.

The calculator above automates these calculations for quick and accurate results.

Related Tools & Guides

Explore our other mathematical calculators and guides for more learning:

Percentage Calculator - Dedicated calculator for all percentage calculations.
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Frequently Asked Questions

What is the basic formula for calculating percentage?

The basic formula is: Percentage = (Part / Whole) × 100. For example, if you have 20 apples out of 100 fruits, the percentage of apples is (20/100) × 100 = 20%.

How do I calculate percentage increase or decrease?

Percentage change = ((New Value - Old Value) / Old Value) × 100. If the result is positive, it's an increase; if negative, it's a decrease. For example, if a price increases from $100 to $120, the percentage increase is ((120-100)/100) × 100 = 20%.

How do I add or subtract a percentage from a number?

To add X% to a number, multiply by (1 + X/100). To subtract X%, multiply by (1 - X/100). For example, to add 15% to 200: 200 × 1.15 = 230. To subtract 15% from 200: 200 × 0.85 = 170.