How to Use the Percentage Calculator

Our percentage calculator makes all percentage calculations simple:

1. Select the type of calculation you need (percentage of, increase/decrease, etc.)
2. Enter the required numbers in the input fields
3. Click "Calculate" to get instant results
4. View detailed step-by-step solutions
5. Use the results for shopping, grades, tips, or any percentage need

Common Percentage Calculations

Here are the most common percentage calculations people need:

1. Calculate X% of Y

Formula: (X ÷ 100) × Y

Example: What is 30% of 200?

Solution: (30 ÷ 100) × 200 = 0.30 × 200 = 60

2. What Percent is X of Y?

Formula: (X ÷ Y) × 100

Example: What percent is 45 of 180?

Solution: (45 ÷ 180) × 100 = 0.25 × 100 = 25%

3. Percentage Increase

Formula: ((New - Old) ÷ Old) × 100

Example: Price increased from $80 to $100

Solution: ((100 - 80) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% increase

4. Percentage Decrease

Formula: ((Old - New) ÷ Old) × 100

Example: Price decreased from $100 to $75

Solution: ((100 - 75) ÷ 100) × 100 = (25 ÷ 100) × 100 = 25% decrease

Real-World Percentage Uses

Percentages are used everywhere in daily life:

• Shopping & Discounts: Calculate sale prices and savings (30% off, buy one get 50% off)
• Restaurant Tips: Calculate appropriate tips (15%, 18%, 20% of bill)
• Academic Grades: Convert test scores to percentages and GPAs
• Finance & Investing: Calculate interest rates, returns, and growth
• Sales & Commission: Calculate sales commissions and bonuses
• Taxes: Calculate sales tax, income tax, and VAT
• Statistics: Express data as percentages for easy comparison
• Health & Fitness: Track body fat percentage, weight loss progress
• Business Metrics: Calculate profit margins, growth rates, market share

Percentage Calculation Examples

Shopping Discount Example

Problem: A $150 jacket is on sale for 40% off. What's the sale price?
Step 1: Calculate discount: 40% of $150 = (40 ÷ 100) × 150 = $60
Step 2: Subtract from original: $150 - $60 = $90
Answer: Sale price is $90 (you save $60)

Restaurant Tip Example

Problem: Your restaurant bill is $85. You want to leave a 20% tip.
Step 1: Calculate tip: 20% of $85 = (20 ÷ 100) × 85 = $17
Step 2: Add to bill: $85 + $17 = $102
Answer: Total payment is $102 (tip is $17)

Grade Percentage Example

Problem: You got 42 out of 50 questions correct. What's your percentage?
Formula: (Correct ÷ Total) × 100
Solution: (42 ÷ 50) × 100 = 0.84 × 100 = 84%
Answer: Your score is 84% (B grade)

Salary Increase Example

Problem: Your salary increased from $50,000 to $55,000. What's the percentage increase?
Formula: ((New - Old) ÷ Old) × 100
Solution: ((55,000 - 50,000) ÷ 50,000) × 100 = (5,000 ÷ 50,000) × 100 = 10%
Answer: Your salary increased by 10%

Quick Percentage Mental Math Tricks

Calculate percentages quickly in your head:

• 10%: Move decimal point one place left (10% of 250 = 25)
• 5%: Calculate 10% and divide by 2 (5% of 80 = 8 ÷ 2 = 4)
• 20%: Calculate 10% and multiply by 2 (20% of 60 = 6 × 2 = 12)
• 25%: Divide by 4 (25% of 200 = 200 ÷ 4 = 50)
• 50%: Divide by 2 (50% of 90 = 90 ÷ 2 = 45)
• 75%: Calculate 50% and add 25% (75% of 80 = 40 + 20 = 60)
• 15%: Calculate 10%, then add half of that (15% of 100 = 10 + 5 = 15)

Common Percentage Mistakes to Avoid

Don't fall into these common percentage traps:

• Percentage Point vs. Percentage: If something goes from 20% to 30%, that's a 10 percentage point increase, but a 50% relative increase
• Adding Percentages: You can't just add percentages. 20% off then 30% off ≠ 50% off total
• Percentage of Different Bases: 50% of 100 (50) is not the same as 100% of 50 (50), but they equal the same number
• Reverse Percentage: If something decreases 50% then increases 50%, you don't get back to the original (100 → 50 → 75)
• Percentage Greater than 100%: Yes, percentages can exceed 100% (200% means double, 300% means triple)

Percentage Conversion Table

Common percentage conversions for quick reference:

Business & Finance Percentage Applications

Percentages are crucial in business and finance:

• Profit Margin: (Profit ÷ Revenue) × 100. Example: $30 profit on $100 sale = 30% margin
• Markup: (Selling Price - Cost) ÷ Cost × 100. Example: Buy at $50, sell at $75 = 50% markup
• Discount Rate: (Original - Sale Price) ÷ Original × 100
• Interest Rate: Annual percentage rate (APR) on loans and investments
• Growth Rate: Year-over-year percentage change in revenue, users, etc.
• Market Share: (Company Sales ÷ Total Market Sales) × 100
• Return on Investment (ROI): (Gain - Cost) ÷ Cost × 100