％ Percentage Calculator
Five everyday percentage calculations on one page. Results update as you type.
Quick note
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Copy all five results at once
How to use
Each of the five boxes is its own calculator. Type into any of them and the result appears right below it. The panel on the right collects all five so you can copy them in one click. It works for prices, grades, tips, sales tax, stock returns, survey results, or any other numbers.
Percentage formulas
| What you want | Formula | Example |
|---|---|---|
| B% of A | A × B ÷ 100 | 15% of 80 = 12 |
| A is what % of B | A ÷ B × 100 | 37 of 120 = 30.83% |
| Percent change | (new − old) ÷ |old| × 100 | 48,000 → 54,000 = +12.5% |
| Increase / decrease by B% | A × (1 ± B ÷ 100) | 39 + 20% = 46.8 |
| Original price before discount | sale price ÷ (1 − discount ÷ 100) | 31.20 at 20% off → 39 |
Common everyday uses
- Tip: 18% of a $64 bill → box ① with A = 64, B = 18 → $11.52.
- Sales tax: $49.99 plus 8.25% tax → box ④ "increased by" → $54.11.
- Test score: 42 out of 50 → box ② → 84%.
- Raise: salary from $62,000 to $66,000 → box ③ → 6.45% increase.
- Sale price: paid $72 at 40% off → box ⑤ → original $120.
Percent vs. percentage points
If an interest rate goes from 3% to 4%, it rose by 1 percentage point, which is a 33.3% increase. News stories about rates, polls and unemployment often mix these up, so check which one is meant.
Up 20%, then down 20%: are you back where you started?
No. 100 up 20% is 120, and 120 down 20% is 96. The second percentage is taken from a different base. The same thing happens with investments: a stock that falls 50% needs a 100% gain to recover.
FAQ
How do I calculate a percentage of a number?
Multiply the number by the percent and divide by 100. For example, 15% of 80 = 80 × 15 ÷ 100 = 12. Use box ①.
How do I calculate percent increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 48,000 to 54,000 is (54,000 − 48,000) ÷ 48,000 × 100 = 12.5%.
What is the difference between percent and percentage points?
Percentage points measure the plain difference between two percentages (3% → 4% is +1 point). Percent change measures the relative change (3% → 4% is +33.3%).
How do I find the original price after a discount?
Divide the sale price by (1 − discount ÷ 100). A $31.20 item at 20% off was originally 31.20 ÷ 0.8 = $39. Use box ⑤.
If a stock drops 50%, how much does it need to gain to break even?
100%. A drop from 100 to 50 needs +50, which is 100% of 50. Try it in box ③ with 50 → 100.
How do I add sales tax to a price?
Use box ④ with the price as A and the tax rate as B, and read the “increased by” line. $49.99 at 8.25% is $54.11.