Percentage Calculator Guide

Master percentage calculations with our comprehensive guide. Learn formulas, see examples, and understand how to use our free online percentage calculator.

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What You'll Learn

  • Basic percentage calculations
  • Percentage change (increase/decrease)
  • Markup and discount calculations
  • Compound interest over time
  • Real-world examples and formulas
  • Tips for accurate calculations

Basic Percentage Calculations

What is X% of Y?

Calculate what percentage of a number represents. This is the most common percentage calculation used in daily life.

Formula: Result = (Percentage × Number) ÷ 100
Example: What is 15% of 200?
15% × 200 ÷ 100 = 30
Example: What is 25% of 80?
25% × 80 ÷ 100 = 20

X is what percent of Y?

Find what percentage one number represents of another. Useful for understanding proportions and ratios.

Formula: Percentage = (Number ÷ Total) × 100
Example: 50 is what percent of 200?
(50 ÷ 200) × 100 = 25%
Example: 30 is what percent of 150?
(30 ÷ 150) × 100 = 20%

Percentage Change (Increase/Decrease)

Calculate how much a value has increased or decreased as a percentage. Essential for analyzing growth, sales performance, and financial changes.

Formula: Percentage Change = ((New Value - Old Value) ÷ Old Value) × 100

Percentage Increase

Example: Price increased from $100 to $120
((120 - 100) ÷ 100) × 100 = 20% increase
Example: Sales grew from 500 to 750 units
((750 - 500) ÷ 500) × 100 = 50% increase

Percentage Decrease

Example: Price decreased from $200 to $160
((160 - 200) ÷ 200) × 100 = -20% (20% decrease)
Example: Temperature dropped from 80°F to 60°F
((60 - 80) ÷ 80) × 100 = -25% (25% decrease)

Markup and Discount Calculations

Markup Calculator

Add a percentage markup to the original price. Essential for retail, pricing strategies, and profit calculations.

Formula: Final Price = Original Price × (1 + Markup Percentage)
Example: Add 30% markup to $50
$50 × (1 + 0.30) = $65
Example: Add 25% markup to $80
$80 × (1 + 0.25) = $100

Discount Calculator

Calculate the final price after applying a percentage discount. Perfect for sales, promotions, and clearance pricing.

Formula: Final Price = Original Price × (1 - Discount Percentage)
Example: 20% discount on $100
$100 × (1 - 0.20) = $80
Example: 15% discount on $200
$200 × (1 - 0.15) = $170

Compound Interest Calculator

Calculate how money grows over time with compound interest. Essential for investments, savings, and long-term financial planning.

Formula: Final Amount = Principal × (1 + Rate)^Time
Example: $1,000 invested at 5% for 10 years
$1,000 × (1 + 0.05)^10 = $1,628.89
Example: $5,000 invested at 8% for 5 years
$5,000 × (1 + 0.08)^5 = $7,346.64

Tips for Accurate Percentage Calculations

1. Always Check Your Work

Use reverse calculations to verify your results. If 15% of 200 is 30, then 30 should be 15% of 200.

2. Understand the Context

Make sure you're calculating the right percentage for your situation. Is it markup, discount, or change?

3. Use Precise Numbers

For financial calculations, use at least 2 decimal places. For general use, whole numbers are often sufficient.

4. Consider Time Periods

For compound interest, ensure your rate and time period match (annual rate with years, monthly rate with months).

Frequently Asked Questions

How do I calculate percentage increase?

Use the formula: ((New Value - Old Value) ÷ Old Value) × 100. For example, if a price increases from $100 to $120, the percentage increase is ((120 - 100) ÷ 100) × 100 = 20%.

What's the difference between markup and margin?

Markup is calculated on the cost price, while margin is calculated on the selling price. Markup = (Selling Price - Cost) ÷ Cost, Margin = (Selling Price - Cost) ÷ Selling Price.

How does compound interest work?

Compound interest means you earn interest on both your principal and the accumulated interest. The formula is: Final Amount = Principal × (1 + Rate)^Time.

Can I use this calculator for business calculations?

Yes! Our percentage calculator is perfect for business use including pricing, profit margins, sales analysis, and financial planning.

Ready to Start Calculating?

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