Percentage Calculator - Calculate Percentages Instantly
Calculate percentages, percentage changes, and solve percentage problems with our comprehensive calculator. Perfect for discounts, tips, grades, and financial calculations.
Basic Percentage Calculator
Calculate what percentage of a number is another number.
Common Percentage Calculations
Basic Percentage
Find X% of a number
Percentage Change
Calculate increase/decrease
Percentage of Total
What % is X of Y?
Add/Subtract %
Increase or decrease by %
Percentage Formula Reference
Basic Formulas
Change Formulas
Understanding Percentages: A Complete Guide
A percentage is a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred." Percentages are used everywhere in daily life—from calculating sales tax and discounts to understanding interest rates and test scores.
Understanding how to calculate and work with percentages is an essential life skill. Whether you're shopping during a sale, calculating tips at restaurants, analyzing financial data, or tracking your academic progress, percentage calculations help you make informed decisions quickly.
The Basic Percentage Formula
Core Percentage Formulas
Real-World Percentage Examples
Shopping Discount Example
A jacket costs $120 and is on sale for 25% off. How much do you save?
Discount = $120 × 0.25 = $30
Final Price = $120 - $30 = $90
Restaurant Tip Example
Your dinner bill is $85. You want to leave an 18% tip. How much is the tip?
Tip = $85 × 0.18 = $15.30
Total = $85 + $15.30 = $100.30
Common Percentage Calculations Explained
1. Finding What Percentage One Number Is of Another
This is useful when you want to know what portion something represents. For example, "What percentage of my income goes to rent?"
Example: You scored 42 out of 50 on a test.
Percentage = (42 / 50) × 100 = 84%
2. Calculating Percentage Increase or Decrease
Used to measure change over time, such as salary increases, price changes, or population growth.
Example: Gas price increased from $1.40 to $1.68 per liter.
% Increase = ((1.68 - 1.40) / 1.40) × 100 = 20%
3. Finding the Original Price Before Discount
When you know the sale price and discount percentage, you can calculate the original price.
Example: Sale price is $60 after a 25% discount.
Original Price = $60 / (1 - 0.25) = $60 / 0.75 = $80
4. Calculating Percentage Points vs. Percentage Change
Important distinction: If interest rates go from 5% to 7%, that's a 2 percentage point increase, but a 40% relative increase.
Example: Interest rate changes from 5% to 7%
Percentage Points = 7% - 5% = 2 points
Percentage Change = ((7 - 5) / 5) × 100 = 40%
Quick Percentage Conversion Reference
| Percentage | Decimal | Fraction | Common Use |
|---|---|---|---|
| 10% | 0.10 | 1/10 | Quick tip calculation |
| 15% | 0.15 | 3/20 | Standard restaurant tip |
| 20% | 0.20 | 1/5 | Good service tip |
| 25% | 0.25 | 1/4 | Common discount |
| 33.33% | 0.3333 | 1/3 | One-third off sales |
| 50% | 0.50 | 1/1 | Complete/whole amount |
Mental Math Tricks for Percentages
10% Trick
To find 10% of any number, simply move the decimal point one place to the left. 10% of $45.00 = $4.50
5% Trick
Find 10% first, then divide by 2. For 5% of $80: 10% = $8, so 5% = $4
15% Trick
Find 10%, then add half of that. For 15% of $60: 10% = $6, half = $3, total = $9
20% Trick
Find 10% and double it. For 20% of $50: 10% = $5, doubled = $10
25% Trick
Divide by 4 (since 25% = 1/4). For 25% of $100: $100 ÷ 4 = $25
50% Trick
Simply divide by 2 (since 50% = 1/2). For 50% of $86: $86 ÷ 2 = $43