Percentage Calculator
Percentages appear everywhere: shopping discounts, salary raises, commissions, taxes, and statistics. This calculator has three modes to solve the most common cases: calculate what a percentage of a number is, find what percentage one number represents of another, and apply a percentage increase or decrease to any value.
The result updates automatically.
Result
Percentage
Final value
Publicidad
How it works
Mode 1 — X% of Y answers "how much is a percentage of a number": result = Y × (X / 100). To get 15% of 200, compute 200 × 0.15 = 30. Mode 2 — X is what % of Y answers "what slice one number is of another": result = (X / Y) × 100. If 30 people out of 200 chose an option, that is (30 / 200) × 100 = 15%. Mode 3 — Increase/Decrease applies a change to a starting value: final = Y × (1 + X/100) for a rise, Y × (1 − X/100) for a drop. A price of 200 with a 15% increase becomes 200 × 1.15 = 230; with a 15% discount it becomes 200 × 0.85 = 170. Notice that these three questions are the same relationship seen from three angles — the part, the whole and the percentage — so knowing any two always yields the third. All three modes use direct arithmetic with no approximation.
Everyday percentage problems at a glance
Almost every percentage you meet in daily life is one of the three modes above. The table collects the most common situations with the exact operation and a worked example, so you can recognise which mode you need and check the result by hand.
| Situation | How to calculate it | Example |
|---|---|---|
| Tip at a restaurant (15%) | bill × 0.15 | 60.00 × 0.15 = 9.00 |
| Discount on a jacket (30%) | price × (1 − 0.30) | 80.00 × 0.70 = 56.00 |
| Add sales tax (21%) | net × 1.21 | 100.00 × 1.21 = 121.00 |
| Salary raise (8%) | salary × 1.08 | 2,000.00 × 1.08 = 2,160.00 |
| Sales commission (3%) | sale × 0.03 | 1,500.00 × 0.03 = 45.00 |
| What % did you sell? | (part ÷ total) × 100 | (45 ÷ 180) × 100 = 25% |
| Test score | (correct ÷ questions) × 100 | (34 ÷ 40) × 100 = 85% |
Publicidad
Preguntas frecuentes
- How do I calculate X% of a number?
- Multiply the number by X and divide by 100. For example, 15% of $2,000 = 2,000 × 15 / 100 = $300. In this calculator, select Mode 1, enter 15 in the percentage field and 2000 in the value field.
- How do I find what percentage X is of Y?
- Divide X by Y and multiply by 100. For example, if you sold 45 out of 180 products, the percentage sold is (45/180) × 100 = 25%. Use Mode 2 of this calculator.
- How do I calculate a discount?
- A 30% discount on $1,500 is calculated as 1,500 × (1 − 0.30) = $1,050. You can also calculate the discount amount: 1,500 × 0.30 = $450. Mode 3 of this calculator shows both values automatically.
- How do I calculate a salary or price increase?
- A 20% increase on $50,000 results in 50,000 × 1.20 = $60,000. The difference is $10,000. Use Mode 3 with a positive percentage.
- How do I calculate the pre-tax price if I know the price with tax?
- If the price including 10% sales tax is $110, the pre-tax price is 110 / 1.10 = $100. You can also use Mode 2: the tax amount ($10) is X% of $100, result: 10%.
- Why does raising by 50% and then lowering by 50% not return to the start?
- Because each percentage is applied to a different base. Starting from 100, a 50% rise gives 150; a 50% drop is then taken from 150, not from 100, so it subtracts 75 and leaves 75. The increase and the decrease act on different amounts, which is why the two do not cancel out. To undo a 50% rise you would need to drop by 33.3%.
- Can I simply add two percentages together?
- Not when they apply one after another. Two successive 20% discounts are not a 40% discount: 100 → 80 → 64, an effective 36% off. The same goes for increases. You can add percentages only when they refer to the same base — for example the shares of a budget — but chained changes must be multiplied, not summed.