How do I calculate a percentage?
Most percentage questions use one of a few formulas: X% of Y is Y times X divided by 100, and percentage change from A to B is (B minus A) divided by A, times 100. FixDoks's Percentage Calculator covers every common version, from percent of a number to increase, decrease and reverse percentage, updating instantly as you type.
Percentage Calculator at a glance
| Covers | % of, % change, increase/decrease, reverse percentage |
|---|---|
| Processing | In your browser; your files are not uploaded |
| Price | Free |
| Works on | Chrome, Edge, Safari and Firefox on Windows, Mac, Android and iPhone |
How to use Percentage Calculator
- Find the row that matches your question, such as What is 20% of 1500.
- Type your own numbers into the boxes in that row.
- The answer appears on the right as you type. Copy all results with Copy result.
What are the percentage formulas?
A percentage is a number out of 100. Almost every percentage question is one of the forms below.
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | Y × X ÷ 100 | 20% of 1,500 = 300 |
| A is what % of B? | A ÷ B × 100 | 45 of 60 = 75% |
| % change from A to B | (B − A) ÷ A × 100 | 800 to 1,000 = +25% |
| Increase Y by X% | Y × (1 + X ÷ 100) | 500 + 12% = 560 |
| Decrease Y by X% | Y × (1 − X ÷ 100) | 500 − 12% = 440 |
| A is X% of what? | A × 100 ÷ X | 30 is 15% of 200 |
Worked example: marks percentage
You scored 412 out of 500 in board exams. Use the second row: 412 ÷ 500 × 100 = 82.4%. If your total is out of 600 because you took six subjects, divide by 600 instead. Some boards and universities also convert CGPA to percentage with their own formula, such as CGPA × 9.5 used by CBSE for its old CGPA system, so check your board's rule.
Worked example: salary hike
Your monthly salary went from ₹40,000 to ₹46,000. Percentage change = (46,000 − 40,000) ÷ 40,000 × 100 = 15%. If you are offered a 15% hike on ₹40,000, the new salary is 40,000 × 1.15 = ₹46,000.
Common mistakes
- Percentage change is not reversible. A 25% rise from 800 gives 1,000, but a 25% fall from 1,000 gives 750, not 800. Going back needs a 20% fall.
- Percent vs percentage points. A loan rate rising from 6.5% to 7.25% is a rise of 0.75 percentage points, but an 11.5% increase in the rate itself. The last row of the calculator shows the points difference.
- Successive percentages do not add. Two discounts of 20% and 10% give 28% off in total, not 30%. Use the Discount calculator for stacked offers.
- Removing tax. To get the price before 18% GST, divide by 1.18. Do not subtract 18%.
Quick mental tricks
10% of any number is the number with the decimal moved one place left. 5% is half of that, and 1% is the decimal moved two places. So 15% of 2,400 is 240 + 120 = 360. X% of Y equals Y% of X, so 8% of 50 is the same as 50% of 8, which is 4.