Percentage Calculator — Free All-in-One Percent Tool

About the Percentage Calculator

Percentages are everywhere—in store discounts, tax calculations, test scores, stock returns, and tip calculations. Yet many people freeze when asked to calculate 15% of a bill or figure out what percentage a raise represents. Our percentage calculator handles every common percentage scenario instantly:

• What is X% of Y? (e.g., What is 20% of $150?)
• X is what percent of Y? (e.g., $30 is what percent of $150?)
• Percentage increase/decrease (e.g., What is the percent change from 80 to 100?)
• Percentage difference between two values

Common Percentage Calculations

1. Finding a Percentage of a Number

Formula: (Percentage ÷ 100) × Number

Example: What is 15% of $200? (15 ÷ 100) × 200 = 0.15 × 200 = $30

2. Finding What Percentage One Number Is of Another

Formula: (Part ÷ Whole) × 100

Example: 45 out of 60 on a test (45 ÷ 60) × 100 = 0.75 × 100 = 75%

3. Percentage Increase

Formula: ((New Value - Original Value) ÷ Original Value) × 100

Example: Salary increased from $50,000 to $55,000 ((55,000 - 50,000) ÷ 50,000) × 100 = (5,000 ÷ 50,000) × 100 = 10% increase

4. Percentage Decrease

Formula: ((Original Value - New Value) ÷ Original Value) × 100

Example: A stock dropped from $80 to $68 ((80 - 68) ÷ 80) × 100 = (12 ÷ 80) × 100 = 15% decrease

5. Reverse Percentage (Finding the Original Value)

Formula: Final Value ÷ (1 + (Percentage ÷ 100)) for increases Formula: Final Value ÷ (1 - (Percentage ÷ 100)) for decreases

Example: After a 20% discount, a jacket costs $80. What was the original price? 80 ÷ (1 - 0.20) = 80 ÷ 0.80 = $100

Real-World Applications

Scenario	Calculation Type	Example
Restaurant tip	% of number	18% of $85 bill = $15.30
Sales tax	% of number	8.5% of $120 = $10.20
Discount shopping	% decrease	30% off $80 = save $24, pay $56
Test grades	% of total	38/50 = 76%
Investment return	% increase	$1,000 → $1,150 = 15% return
Population growth	% increase	City grew from 100k to 110k = 10%
Inflation rate	% increase	Prices rose 3.2% year-over-year
Commission	% of number	5% of $50,000 sale = $2,500

Percentage Quick Reference

Fraction	Percentage	Decimal
1/2	50%	0.50
1/3	33.33%	0.333
1/4	25%	0.25
1/5	20%	0.20
1/8	12.5%	0.125
1/10	10%	0.10
1/20	5%	0.05
1/100	1%	0.01

Compound Percentages

When percentages apply sequentially, they multiply, not add:

Example: A $100 item goes up 10%, then down 10%

• After increase: $100 × 1.10 = $110
• After decrease: $110 × 0.90 = $99
• Result: $99 (not $100!)

This is why consecutive percentage changes are not symmetric.

Frequently Asked Questions

How do I calculate a percentage without a calculator?

Use benchmarks: 10% = divide by 10, 5% = half of 10%, 1% = divide by 100. Build from there. For 15%, calculate 10% + 5%.

What's the difference between percentage and percentage points?

Going from 5% to 8% is a 3 percentage point increase, but a 60% increase in the value itself.

How do I calculate cumulative percentage growth over multiple years?

Multiply the growth factors: (1 + r₁) × (1 + r₂) × (1 + r₃) - 1. For 10%, 15%, and 8%: 1.10 × 1.15 × 1.08 - 1 = 36.6% total growth.

Can a percentage be over 100%?

Yes. If you earn $50 on a $25 investment, that's a 200% return. Percentages above 100% simply mean the result is more than double the original.

How do I find what percentage one number is greater than another?

Use the percentage increase formula: ((New - Old) ÷ Old) × 100. If Old is 40 and New is 50: (10 ÷ 40) × 100 = 25% greater.

Related Calculators

• Percentage Change Calculator - Focused percent increase/decrease tool
• Fraction Calculator - Convert between fractions and percentages
• Average Calculator - Calculate mean, median, and mode
• Scientific Calculator - Advanced mathematical functions
• Compound Interest Calculator - See percentage growth over time