Percentage of a Number Calculator

Calculating the percentage of a number is a fundamental math skill used in everyday situations. A percentage represents a portion or fraction of 100. When you calculate "X% of Y," you're finding what portion X represents out of the total Y.

The process is simple: convert the percentage to a decimal by dividing by 100, then multiply by the number. This works for any percentage—from small fractions to values over 100%.

Why Master Percentage Calculations

• Shopping Smarter: Calculate exact savings and compare discounts instantly
• Financial Planning: Understand investment returns, interest rates, and fees
• Accurate Budgeting: Determine exact tax amounts, tips, and commission payments
• Professional Use: Compute sales commissions, profit margins, and business metrics
• Everyday Math: Calculate discounts, tax, tips, and percentage-based adjustments confidently

Example 1: Basic Calculation

Example 2: Real-World Application (Shopping Discount)

Example 3: Decimal Percentages

Example 4: Percentages Over 100%

Shopping & Discounts

When stores advertise sales with percentage discounts, you can quickly calculate your savings. A "25% off" sale means you pay 75% of the original price. Use this calculator to find the exact discount amount and final price you'll pay.

Restaurant Tips

Standard tip percentages are 15% (average service), 18% (good service), or 20% (excellent service). For a $85 dinner bill with 18% tip: (18 ÷ 100) × $85 = $15.30. This calculator makes tipping quick and accurate.

Sales Tax & Price Totals

Sales tax rates vary by location (typically 5-10%). Calculate the tax amount, then add to the original price for your total. For a $250 item with 8% tax: (8 ÷ 100) × $250 = $20 tax. Total: $270.

Investment Returns

When investing, you earn returns as a percentage. A 7.5% annual return on $5,000: (7.5 ÷ 100) × $5,000 = $375 profit. Track investment growth year over year using this method.

Sales Commission

Sales professionals earn commission as a percentage of total sales. A 5% commission on $10,000 in sales: (5 ÷ 100) × $10,000 = $500. Calculate commissions instantly for various sales volumes.

Business Profit Margins

Calculate profit margins to understand business performance. If cost is $100 and profit margin is 30%: (30 ÷ 100) × $100 = $30 profit, so selling price = $130.

You can calculate many percentages quickly in your head using these mental math shortcuts:

Finding 10%

Simply move the decimal point one place to the left.

• 10% of 200 = 20
• 10% of 75.5 = 7.55
• 10% of 1,200 = 120

Finding 5%

5% is half of 10%. Find 10%, then divide by 2.

• 5% of 200 = (10% of 200) ÷ 2 = 20 ÷ 2 = 10
• 5% of 80 = (10% of 80) ÷ 2 = 8 ÷ 2 = 4

Finding 1%

1% is one-hundredth. Move the decimal point two places left.

• 1% of 500 = 5
• 1% of 1,200 = 12

Combining Percentages

Add smaller percentages together to find larger ones:

• 15% = 10% + 5%
• 25% = 10% + 10% + 5%
• 20% = 10% + 10%
• 30% = 10% + 10% + 10%

Finding 50%

50% is simply half the number.

• 50% of 200 = 100
• 50% of 75 = 37.5

Finding 25%

25% is one-quarter. Divide the number by 4.

• 25% of 200 = 50
• 25% of 80 = 20

Example: Calculate 18% of $50 Mentally

Mistake 1: Forgetting to Divide by 100

Mistake 2: Confusing "Percent Off" with "Percent Of"

Mistake 3: Adding Percentages Incorrectly

Mistake 4: Rounding Too Early

Percentage OF (What This Calculator Does)

Finding what percentage X equals: 25% of 100 = 25

Formula: (Percentage ÷ 100) × Number

Percentage OFF (Discount)

Subtracting a percentage from a total: 100 with 25% off = 75

Formula: Number - (Percentage × Number)

What Percentage IS One Number of Another

Finding the percentage: What % is 25 of 100? Answer: 25%

Formula: (Part ÷ Total) × 100

Percentage Increase

How much did something grow: 100 increased by 25% = 125

Formula: Number × (1 + Percentage ÷ 100)

Percentage Decrease

How much did something shrink: 100 decreased by 25% = 75

Formula: Number × (1 - Percentage ÷ 100)