Percentage Calculator
To find X% of a number, multiply the number by X and divide by 100 — and to find what percent one number is of another, divide them and multiply by 100. Enter your values for percentages, percentage change and more.
Every everyday percentage in one place — what is P% of a number, what percent one number is of another, finding the whole, the percentage change between two values, an increase or decrease by a percent, and the percentage difference. Fill in any calculator below and read the answer.
Type your numbers into any calculator and press its Calculate button to see the answer and the working.
How to use this percentage calculator
Percentages turn up everywhere — test scores, discounts, tips, tax, interest, statistics and price moves. Rather than reaching for a different tool each time, this page groups every common percentage calculation in one place. Fill in any calculator above and press its Calculate button; each one shows both the result and the working.
- Common phrases — what is P% of a number, what percent one number is of another, and finding the whole from a part.
- Percentage change — the increase or decrease from an old value to a new one, or a value after increasing or decreasing by a percent.
- Percentage difference — how far apart two numbers are, relative to their average.
Marks, grades and everyday uses
The what-percent calculator doubles as a marks percentage calculator: enter the marks you scored and the total marks and it returns your percentage — for a single subject, a full marksheet, or 10th and 12th class results (marks ÷ total × 100). Use the others for a shop discount, a tip, sales tax, the change or difference between two numbers, or any figure that needs a percent. The maths is identical in the UK, the UAE, India, the US or anywhere else. Converting a GPA from another country instead? Use our GPA to percentage converter.
Worked examples
Percent of a number: 15% of 200 = 200 × 15 ÷ 100 = 30. Percentage change: a value rising from 100 to 150 is (150 − 100) ÷ 100 × 100 = 50% increase. Reverse discount: if a jacket costs 80 after a 20% sale, the original was 80 ÷ 0.80 = 100 — which catches people out, because 80 plus 20% is not 100.
| You want to… | Do this | Example |
|---|---|---|
| Find a percent of a number | value × percent ÷ 100 | 15% of 200 = 30 |
| Turn a fraction into a percent | part ÷ whole × 100 | 45/60 = 75% |
| Find the whole from a part | part ÷ (percent ÷ 100) | 30 is 15% of 200 |
| Measure growth | (new − old) ÷ old × 100 | 100 → 150 = +50% |
| Add tax or a tip | × (1 + percent ÷ 100) | +18% on 50 = 59 |
| Undo a discount | ÷ (1 − percent ÷ 100) | 80 after −20% = 100 |
Percentages are ratios out of 100 — “per cent” literally means “per hundred.”
The percentage formulas
Every tab is one of these standard identities (P is a percent, so 20% means P = 20):
Percent of a number
What percent X is of Y
Find the whole (X is P% of what)
Percentage change (old to new)
Increase or decrease by a percent
Reverse a markup or discount
Worked example — what is 15% of 200?
Result = 15 × 200 ÷ 100
= 3000 ÷ 100 = 30
How to use it & key terms
Pick the type of percentage question, enter your two numbers, then press Calculate for the answer and the working.
| Term | What it means |
|---|---|
| Percentage | A number out of 100 (“per cent” means per hundred). |
| Percent of | X% of Y = (X ÷ 100) × Y. |
| Percentage change | The increase or decrease from one value to another, as a percent. |
| Percentage difference | The gap between two values relative to their average. |
| Percentage points | The plain difference between two percentages (5% to 7% is 2 points). |
| Base / whole | The starting value a percentage is taken from. |
Sources & methodology
Every tab applies a standard percentage identity — percent of a number, what-percent, the reverse (find the whole), percentage change, increasing or decreasing by a percent, and reversing a markup or discount. Each result is computed straight from the numbers you enter, at full precision, and rounded only for display.
All the percentage formulas at a glance
| To find… | Formula |
|---|---|
| X% of a number | percent ÷ 100 × number |
| What percent A is of B | A ÷ B × 100 |
| Find the whole (A is P% of what) | A ÷ (P ÷ 100) |
| Percentage change (old to new) | (new − old) ÷ old × 100 |
| Increase or decrease by a percent | number × (1 ± percent ÷ 100) |
| Percentage difference | |a − b| ÷ ((a + b) ÷ 2) × 100 |
Sources: Standard percentage arithmetic (percent = part ÷ whole × 100).
Percentage traps that trip everyone up
Percentages are simple to calculate and surprisingly easy to misread, and most of the confusion comes down to one question: a percentage of what? The classic trap is the difference between a percentage point and a percent. If an interest rate or a poll share moves from 5% to 6%, that is a rise of one percentage point but a twenty percent increase relative to where it started — two true statements that sound contradictory until you notice they are measuring against different bases. Headlines that say a figure is 'up 3%' when they mean 'up 3 points,' or the reverse, cause real misunderstanding. Naming the base every time — percent of what — clears up most of it.
The second trap is assuming percentage changes are symmetric, when they are not. Go up by ten percent and then down by ten percent and you do not return to where you began: the two apply to different starting values, so you land about one percent lower. The same asymmetry explains why a fifty percent loss needs a one hundred percent gain to recover — halving then doubling — which is why a discount followed by an equal markup never gets back to the original price. Percentages also happily pass one hundred: a value that triples has risen by two hundred percent, not three hundred, and 'three hundred percent of' a number is not the same as 'three hundred percent more than' it. Each of these bites people who reach for the intuitive answer.
A last mistake shows up whenever percentages are combined. You cannot simply average two percentages that come from groups of different sizes — a class where 90% of ten students passed and 50% of forty students passed did not have a 70% pass rate; you have to weight each by its group size to get the true overall figure. The same logic applies to averaging growth rates, discounts or success rates from unequal samples. When in doubt, go back to the raw counts, do the arithmetic on the actual quantities, and convert to a percentage only at the very end. Handle the base carefully and none of these traps can catch you.
- Points are not percent — 5% to 6% is one point but a 20% rise.
- Up then down is not level — a 10% rise then a 10% fall lands below the start.
- Don't average unequal groups — weight each percentage by its size.
Frequently asked questions
How do I find what X% of a number is?
Multiply the number by the percent and divide by 100. 15% of 200 = 200 × 15 ÷ 100 = 30. The percent-of-a-number calculator does it instantly.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 out of 200 is 30 ÷ 200 × 100 = 15%. Use the what-percent calculator.
How do I calculate a vote percentage?
Divide the votes for an option by the total votes cast, then multiply by 100. If a candidate gets 1,200 of 5,000 votes, that’s 1,200 ÷ 5,000 × 100 = 24%. It’s the same “what percent of the total” sum, so it also works for a poll share, a budget slice or progress toward a goal.
How do I find the whole when I know a part and its percentage?
Divide the part by the percent as a decimal. If 30 is 15% of a number, the whole is 30 ÷ 0.15 = 200. The find-the-whole calculator handles this.
How do I calculate a percentage increase or decrease?
Percentage change = (new − old) ÷ old × 100. From 100 to 150 is +50%; a negative result means a decrease.
How do I increase or decrease a number by a percent?
Increase: × (1 + percent ÷ 100). Decrease: × (1 − percent ÷ 100). 200 up 10% = 220; down 10% = 180.
How do I reverse a percentage to find the original price?
Divide the final price by 1 plus or minus the percent as a decimal. 120 after a 20% markup came from 120 ÷ 1.20 = 100; 80 after a 20% discount came from 80 ÷ 0.80 = 100.
What is the percentage difference between two numbers?
It compares two numbers relative to their average and is always positive: |a − b| ÷ ((a + b) ÷ 2) × 100. Use it when neither number is a starting point.
Is percentage change the same as percentage difference?
No. Change has a direction (old to new) and can be positive or negative; difference divides by the average of the two values and is always positive.
How do I turn a fraction or decimal into a percent?
Multiply by 100 and add a percent sign. 0.25 becomes 25%, and 3/4 = 0.75 becomes 75%. Divide by 100 to go back.
Can I use it for discounts, tips, tax and grades?
Yes. Increase or decrease by a percent for tips and tax, percent-of-a-number for a sale saving, what-percent for a test score, and the change or difference calculators for two numbers.
How do I calculate my marks percentage?
Use the what-percent calculator: enter the marks you scored as the first number and the total marks as the second. For example, 425 out of 500 is 425 ÷ 500 × 100 = 85%. For a whole marksheet, add up all the marks scored and all the maximum marks, then do the same.
How do I calculate a percentage in Excel or Google Sheets?
For X% of a value use =value*percent/100 (for example =200*15/100). For what percent A is of B use =A/B and format the cell as a percentage, or =A/B*100 for a plain number. For percentage change use =(new-old)/old*100.
How do I find a percentage of a percentage?
Convert each percent to a decimal and multiply, then multiply by 100. For example, 50% of 20% is 0.5 × 0.2 = 0.1, which is 10%. In the calculator, use the percent-of-a-number tab and enter one of the percentages as the number.
How do I find the percentage difference in Excel?
Percentage difference compares two numbers against their average. In Excel or Google Sheets, put the values in A1 and B1, then use =ABS(A1-B1)/((A1+B1)/2)*100. For a plain percentage change from old to new instead, use =(B1-A1)/A1*100. Format the cell as a percentage for the % sign.