Percentage Calculator
Choose a calculation type, enter your numbers, and click calculate.
Why a percentage calculator is so useful
Percentages show up everywhere: discounts, grades, taxes, savings rates, tips, inflation, and business reporting. A quick percentage tool saves time and prevents small arithmetic mistakes that can cost real money. This page gives you a practical, all-in-one way to figure out percentages in seconds.
If you've ever paused to ask “How much is 18% off?”, “What percent did this value change?”, or “What percentage is this number of the total?”, you're using core percentage math. The calculator above handles all of those common tasks.
How to use the calculator
1) What is X% of Y?
Use this when you want to find a portion of a number. Example: 15% of 240.
2) X is what % of Y?
Use this when comparing one value to a total. Example: 36 is what percent of 180?
3) Percentage increase or decrease
Use this to measure growth or decline between two values. Example: from 50 to 65.
4) Add or subtract a percentage
Use this for markups, price increases, discounts, or reductions.
Real-world percentage examples
- Shopping: A $80 item with a 25% discount saves $20, so you pay $60.
- Restaurant tips: 18% tip on a $45 bill is $8.10.
- Grades: 42 correct out of 50 is 84%.
- Investing: If an investment rises from $1,000 to $1,150, the gain is 15%.
- Budgeting: If rent is $1,200 of a $3,000 income, rent is 40% of monthly income.
Common mistakes when figuring percentages
- Confusing percentage points with percent change.
- Forgetting to divide by 100 when converting a percent to decimal.
- Using the wrong base value in comparisons.
- Ignoring the sign on change (positive vs. negative growth).
- Rounding too early and carrying forward errors.
Percentage points vs percent change
These are not the same. If interest rates move from 3% to 4%, that is a 1 percentage point increase, but a 33.33% percent increase relative to the original 3%. In finance, policy, and analytics, that distinction matters.
Quick mental math tips
- 10% is easy: move the decimal one place left.
- 5% is half of 10%.
- 20% is double 10%.
- 1% is 10% divided by 10.
- For 15%, do 10% + 5%.
Final thoughts
Mastering percentages is one of the most practical math skills you can have. Whether you're checking a sale, analyzing business performance, or calculating growth, these tools help you make faster and more accurate decisions.
Bookmark this page and use the calculator any time you need to figure out percentages confidently.