Percentage Calculator

Five percentage calculators in one tool. Find a percentage of a number, determine what percent one number is of another, calculate percentage change, or increase and decrease values by a percentage. Formulas included.

Common Percentage Reference Table

% of 50 of 100 of 200 of 500 of 1,000 Fraction Decimal

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How to Calculate Percentages: Complete Guide

Percentages are one of the most widely used mathematical concepts in daily life. From calculating discounts while shopping to understanding investment returns, percentage calculations are everywhere. This guide covers the five most common types of percentage problems and how to solve them.

1. Finding X% of a Number

This is the most basic percentage calculation. To find X% of Y, multiply Y by X and divide by 100. For example, to find 20% of $150: 150 × 20 ÷ 100 = $30. You'll use this for calculating tips, taxes, discounts, and commissions.

2. Finding What Percent X is of Y

When you need to express a relationship as a percentage, divide the part by the whole and multiply by 100. If you scored 45 out of 60 on a test: (45 ÷ 60) × 100 = 75%. This is essential for grading, statistics, and performance metrics.

3. Percentage Change

Percentage change measures how much a value has increased or decreased relative to its original value. The formula is: ((New − Old) ÷ Old) × 100. If your rent went from $1,200 to $1,350: ((1350 − 1200) ÷ 1200) × 100 = 12.5% increase. This is crucial for tracking price changes, growth rates, and financial performance.

4. Increasing a Number by a Percentage

To increase a value by a percentage, multiply it by (1 + percent/100). To add a 20% markup to a $50 item: 50 × 1.20 = $60. This is used for price markups, salary raises, tax-inclusive pricing, and growth projections.

5. Decreasing a Number by a Percentage

To decrease a value by a percentage, multiply it by (1 − percent/100). A $80 item with a 25% discount: 80 × 0.75 = $60. This applies to sale prices, depreciation, population decline, and budget cuts.

Common Percentage Conversions

Real-World Applications

Frequently Asked Questions

How do I calculate a percentage of a number?
To find X% of Y, multiply Y by X and divide by 100. For example, 15% of 200 = 200 × 15 ÷ 100 = 30. This is the most common percentage calculation used in discounts, tips, and taxes.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, to find what percent 30 is of 200: (30 ÷ 200) × 100 = 15%. This tells you the proportion as a percentage.
What is the formula for percentage change?
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result means an increase, and a negative result means a decrease. For example, going from 80 to 100 is a 25% increase.
How do I increase a number by a percentage?
Multiply the number by (1 + percentage/100). For example, to increase 200 by 15%: 200 × 1.15 = 230. This is commonly used for price increases, salary raises, and growth projections.
How do I decrease a number by a percentage?
Multiply the number by (1 − percentage/100). For example, to decrease 200 by 15%: 200 × 0.85 = 170. This is used for discounts, depreciation, and reductions.
What is the difference between percentage change and percentage difference?
Percentage change measures how much a value changed from an original value (has direction — increase or decrease). Percentage difference compares two values without a clear 'original' — it uses the average of the two values as the base.
Can a percentage be more than 100%?
Yes. A percentage over 100% means more than the whole. For example, if sales grew from $50K to $120K, that's a 140% increase. Similarly, 200% of 50 is 100 — double the original value.

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Methodology, Assumptions, and Limitations

This calculator uses standard percentage formulas: percent of a value = base × (percent ÷ 100), percentage change = ((new − old) ÷ old) × 100, percentage increase = base × (1 + percent ÷ 100), and percentage decrease = base × (1 − percent ÷ 100). Results are arithmetic estimates only and are rounded for readability.

Percentages can become misleading when the starting value is zero, when values are entered with inconsistent units, or when a real-world situation includes taxes, fees, compounding, or time-based effects not modeled here. Use the outputs as a quick math reference rather than a substitute for contract, pricing, or financial planning review.

Editorial Transparency

Last updated: March 9, 2026 · Author: CalcSharp Editorial Team · Reviewed by: CalcSharp Finance Review Desk

Sources and references: Standard percentage arithmetic taught in general mathematics curricula, plus CalcSharp's editorial policy and corrections process.