The percentage button does one thing: it converts what you typed into a percentage of another number
Most calculators have a % button. When you press it, the calculator takes the number on your screen and expresses it as a percentage of the number you entered before. On a standard calculator, the % button sits near the multiplication and division buttons, usually in the right column.
The percentage button is not the same as typing the percent symbol. It performs a calculation. If you want to know what 15% of 80 is, you do not type 15, then %, then 80. You type 15, then %, then 80, then =. The calculator then shows you 12 — because 15% of 80 equals 12.
Different calculators work slightly differently. A basic four-function calculator (the kind with just +, −, ×, ÷) uses the % button one way. A scientific calculator uses it another. A phone calculator or computer calculator may have a % button that works differently still. This guide covers the most common versions.
Key Takeaways
- The % button converts a number into a percentage of another number — it performs a calculation, not just a symbol.
- On a basic calculator, enter the percentage amount, press %, enter the base number, then press = to get the result.
- To find a percentage of a total (like 20% of 150), use the multiplication method: enter 150, press ×, enter 20, press %, then =.
- To find what percentage one number is of another, divide the first by the second and press % to see the result as a percentage.
- Phone and computer calculators often have a % button that works the same way as basic calculators, but always test with a number you know first.
Finding the percentage button on your calculator
On a physical calculator, the % button is almost always in the bottom right area, near the equals button or in the same column as the multiplication and division buttons. Look for a button labeled with the symbol %. On some older or very basic calculators, it may be labeled PERCENT instead.
On a phone or computer, open the calculator app and look for the % symbol. On most phones, you may need to rotate the screen to landscape mode to see more buttons, including the % button. On a computer, the calculator app (called Calculator on Windows, Calculator on Mac) has a % button in the standard view.
If you cannot find a % button, your calculator may not have one. Very basic calculators sometimes lack this button. In that case, you can still calculate percentages by hand using division and multiplication, which is covered in a later section.
How to calculate a percentage of a number
This is the most common use: finding what 20% of 150 is, or what 8% of a price is. The steps are: enter the base number, press multiply, enter the percentage, press the % button, then press equals.
Example: Find 20% of 150.
- Enter 150
- Press × (multiply)
- Enter 20
- Press %
- Press =
- Your screen shows 30
This works because the % button tells the calculator to treat 20 as a percentage (0.20) and multiply it by 150. The result is 30.
Another example: Find 8% of 250.
- Enter 250
- Press ×
- Enter 8
- Press %
- Press =
- Your screen shows 20
How to add or subtract a percentage from a number
This is useful for calculating a sale price (subtracting a discount) or a total with tax (adding a percentage). The steps are almost the same as finding a percentage of a number, but you press + or − instead of ×.
Example: A shirt costs $40 and is on sale for 25% off. What is the new price?
- Enter 40
- Press − (subtract)
- Enter 25
- Press %
- Press =
- Your screen shows 30
The shirt now costs $30. The calculator subtracted 25% of $40 (which is $10) from the original price.
Example: A meal costs $50 before tax. The tax is 8%. What is the total?
- Enter 50
- Press + (add)
- Enter 8
- Press %
- Press =
- Your screen shows 54
The total is $54. The calculator added 8% of $50 (which is $4) to the original price.
How to find what percentage one number is of another
Sometimes you know two numbers and want to know what percentage the first is of the second. For example, if you scored 18 out of 25 on a test, what percentage is that?
The steps are: enter the first number, press divide, enter the second number, press %, then press equals.
- Enter 18
- Press ÷ (divide)
- Enter 25
- Press %
- Press =
- Your screen shows 72
Your score is 72%. The calculator divided 18 by 25 (which equals 0.72) and the % button converted that to a percentage.
Another example: You saved $150 toward a $500 goal. What percentage of your goal have you saved?
- Enter 150
- Press ÷
- Enter 500
- Press %
- Press =
- Your screen shows 30
You have saved 30% of your goal.
What to do if your calculator does not have a percentage button
If your calculator has no % button, you can still calculate percentages using only multiplication and division. The method is slightly longer but gives the same answer.
To find a percentage of a number without the % button, divide the percentage by 100, then multiply by the base number. Example: Find 20% of 150.
- Enter 20
- Press ÷
- Enter 100
- Press =
- Your screen shows 0.2
- Press ×
- Enter 150
- Press =
- Your screen shows 30
You get the same result (30) as you would with the % button. This method works on any calculator that has division and multiplication, even very basic ones.
Common mistakes when using the percentage button
The most common mistake is pressing the % button at the wrong step. If you want to find 20% of 150, you must press % after you enter 20, not after you enter 150. Pressing % in the wrong place gives you the wrong answer.
Another mistake is forgetting to press = at the end. Some calculators show a partial result when you press %, but the final answer only appears when you press =. If you read the number off the screen before pressing =, you may get an incomplete result.
A third mistake is using the % button when you mean to type a percent symbol. If you want to enter the number 5% as a value (not calculate 5% of something), you type 5, then 0, then 0, then divide by 100 — or you just type 0.05. Do not press the % button, because that will try to calculate a percentage instead of entering a value.
Frequently Asked Questions
Why does my calculator give a different answer when I press % than when I divide by 100?
It should not, if you are using the % button correctly. The % button is a shortcut for dividing by 100 and multiplying. If you get different answers, you may be pressing % at a different step than you think. Try the same calculation twice — once with the % button and once by dividing by 100 — and compare each step to find where they differ.
Can I use the percentage button on my phone calculator the same way as a physical calculator?
Usually yes, but not always. Phone calculators vary by model and operating system. The safest approach is to test your phone calculator with a percentage you already know the answer to — like 50% of 100, which should be 50. If it works, you can use it the same way as a physical calculator. If it does not, try the division-by-100 method instead.
What if I need to calculate a percentage increase or decrease between two numbers?
Subtract the smaller number from the larger one, divide the result by the original number, then press %. For example, if a price went from $50 to $65, subtract 50 from 65 (result: 15), divide 15 by 50, press %, then press =. The answer is 30% — the price increased by 30%.
Can the percentage button help me calculate tips?
Yes. Enter the bill amount, press +, enter the tip percentage (like 18), press %, then press =. The calculator shows the total with tip included. If you want to see just the tip amount, enter the bill, press ×, enter the tip percentage, press %, then press = instead.