Percentage Calculator
Calculate Percentages
Enter a percentage and a base number to instantly calculate the exact fractional amount.
This calculator also automatically computes the total if the percentage is added (like calculating a restaurant tip or tax) or subtracted (like calculating a sale discount at a store).
How to Use this Calculator
Using the calculator is simple:
- Input Percentage: Enter the percent you want to find (e.g., 20).
- Input Base Number: Enter the total original number (e.g., 150).
- View Results: The blue results card will automatically calculate the exact amount, as well as the addition/subtraction totals.
Tip: Use the Quick Select checkbox to automatically fill in common percentages for tips or standard store discounts.
Percentage Formula
The word "percent" literally means "per one hundred." To find a percentage of a number, you divide the percentage by 100 (which turns it into a decimal), and then multiply it by the base number.
Result = (Percentage ÷ 100) × Base Number
Example
If you want to leave a 20% tip on a $45.00 restaurant bill:
Decimal = 20 ÷ 100 = 0.20
Tip Amount = 0.20 × 45 = $9.00
Therefore, the tip is $9.00. If you want the total bill, you simply add the $9.00 tip to the $45.00 base, making it $54.00 total.
Common Use Cases & Examples
Percentages are used every day in finance, shopping, and mathematics. Here are some common examples of when people need this tool:
| Use Case | Example Situation | Why Users Need It | Result |
|---|---|---|---|
| Restaurant Tipping | What is 20% of $65? | Calculating how much to leave a waiter | $13.00 |
| Retail Discounts | What is 30% off of $120? | Finding the sale price of an item | $36.00 (Total: $84.00) |
| House Down Payments | What is 20% of $300,000? | Budgeting cash needed to buy a home | $60,000 |
| Tithing | What is 10% of $4,000? | Calculating a standard religious tithe on a paycheck | $400.00 |
| Investment Returns | What is 8% of $10,000? | Estimating annual stock market yields | $800.00 |
Quick Percentages Reference
Many common percentages can be calculated in your head if you know the fraction they represent. Here is a cheat sheet:
| Percentage | Fraction Equivalent | Mental Math Trick |
|---|---|---|
| 10% | 1/10 | Move the decimal point one place to the left. |
| 20% | 1/5 | Find 10% and double it. |
| 25% | 1/4 | Divide the number in half, then divide in half again. |
| 33.3% | 1/3 | Divide the number by 3. |
| 50% | 1/2 | Divide the number by 2. |
| 75% | 3/4 | Divide by 4, then multiply by 3. |