The percentage button does one thing: it converts what you typed into a percentage of another number
Most calculators have a % button that sits near the multiplication and division keys. When you press it, the calculator takes the number on your screen and treats it as a percentage of the number you entered before. This is faster than doing the math yourself — instead of multiplying by 0.15 to find 15 percent of something, you type the numbers and let the button do it.
The exact location of the % button varies by calculator model. On phone calculators, you may need to rotate your phone to landscape mode to see it. On physical calculators, it's usually in the bottom right area, near the equals button. If you can't find it, check your calculator's manual or search for your specific model online.
Key Takeaways
- To find a percentage of a number, enter the number, press %, enter the percentage, then press equals.
- The % button converts your percentage into decimal form automatically, so you don't have to divide by 100 yourself.
- Different calculators may behave slightly differently with the % button, especially when adding or subtracting percentages.
- If your calculator doesn't have a % button, you can still calculate percentages by dividing and multiplying manually.
Finding 15 percent of $80 (the most common use)
This is the calculation people use most often — figuring out a tip, a discount, or a portion of a total. Here's the step-by-step process:
- Type 80 (the number you're finding a percentage of)
- Press × (multiply)
- Type 15 (the percentage you want)
- Press %
- Press =
Your screen will show 12. That's 15 percent of $80. The % button took your 15, converted it to 0.15, and multiplied it by 80 in one step.
This same sequence works for any percentage of any number. If you need 20 percent of 150, you'd type 150 × 20 % =. If you need 8 percent of 2,500, you'd type 2500 × 8 % =. The order is always: the base number, multiply, the percentage, the % button, then equals.
Adding or subtracting a percentage (for sales and markups)
When you're working with a discount or a price increase, the % button works slightly differently. Say an item costs $60 and it's on sale for 25 percent off. You want to know the final price.
- Type 60 (the original price)
- Press − (minus, because it's a discount)
- Type 25 (the discount percentage)
- Press %
- Press =
Your screen shows 45. The item costs $45 after the 25 percent discount. The calculator subtracted 25 percent of $60 (which is $15) from the original $60.
For a markup or price increase, use the plus button instead. If something costs $40 and the price goes up 10 percent, you'd type 40 + 10 % =, and the answer is $44. The % button adds 10 percent of $40 (which is $4) to the original price.
Why your calculator might give a different answer
Not all calculators work the same way with the % button. Some older or simpler models don't have one at all. Some scientific calculators treat the % button differently — they may require you to press equals before the % button, or they may not work with addition and subtraction the same way a basic calculator does.
If you press the % button and get an unexpected result, try this: instead of using the % button, do the math manually. To find 15 percent of 80, divide 15 by 100 (which gives you 0.15), then multiply by 80. Type 15 ÷ 100 × 80 =. You'll get the same answer: 12. This method works on every calculator, even ones without a % button.
Phone calculators sometimes behave differently depending on whether you're in standard or scientific mode. If the % button isn't working the way you expect, try switching modes or checking your phone's calculator settings.
Calculating what percentage one number is of another
Sometimes you need to know the reverse: what percentage is 12 of 80? This tells you things like what portion of your budget you've spent, or what grade you got on a test.
- Type 12 (the part)
- Press ÷ (divide)
- Type 80 (the whole)
- Press =
- Press %
Your screen shows 15. That means 12 is 15 percent of 80. Some calculators will show this as 15 without the percent sign; others will show 15%. Either way, the answer is the same.
If your calculator doesn't give you the right answer with this method, you can also type 12 ÷ 80 = and then multiply the result by 100. That will give you 15, which you then know is a percentage.
Using percentage on your phone's calculator app
The calculator app on your phone works the same way as a physical calculator, but you may need to rotate your phone to landscape mode to see the % button. On iPhone, open the Calculator app and turn your phone sideways — the scientific calculator view will appear with more buttons, including %. On Android, the location varies by phone model, but most have a % button visible in standard mode or accessible by swiping or tapping a menu.
If you can't find the % button on your phone, you can always calculate percentages the manual way: divide the percentage by 100, then multiply by the number. This works on every calculator app without needing to find a special button.
Frequently Asked Questions
What's the difference between pressing % and just typing the decimal?
The % button saves you a step. Instead of converting 15 percent to 0.15 in your head and typing 0.15, you just type 15 and press %. The calculator does the conversion for you. Both methods give the same answer, but the % button is faster.
Why do I get a weird answer when I use the % button?
Different calculators handle the % button differently, especially with addition and subtraction. If you're getting an unexpected result, try the manual method instead: divide the percentage by 100, then multiply or divide by your base number. This works consistently on every calculator.
Can I use the % button to calculate tips?
Yes. To calculate a 20 percent tip on a $45 bill, type 45 × 20 % =. The answer is $9. Some phones have calculator apps with a dedicated tip button that does this automatically, but the % button method works just as well.
What if my calculator doesn't have a % button?
You can still calculate percentages by hand. To find 15 percent of 80, type 15 ÷ 100 × 80 =. To find what percentage 12 is of 80, type 12 ÷ 80 × 100 =. It takes one extra step, but the answer is the same.
Do I need to press equals after the % button?
Usually yes. Most calculators show the percentage result when you press %, but you need to press = to confirm and complete the calculation. Some scientific calculators work differently, so check your manual if you're unsure.