📊 Free Percentage Calculator
Calculate any percentage instantly. Find percentages of numbers, calculate increases and decreases, or find the percentage difference between values.
Calculate any percentage instantly. Find percentages of numbers, calculate increases and decreases, or find the percentage difference between values.
A percentage is a number expressed as a fraction of 100. The word comes from Latin "per centum" meaning "by the hundred." Percentages are one of the most practical mathematical concepts used in everyday life.
| Percentage | Decimal | Fraction | How to Convert |
|---|---|---|---|
| 45% | 0.45 | 9/20 | Divide by 100 for decimal |
| 0.75 (decimal) | 0.75 | 3/4 | Multiply by 100 for percent |
| 2/5 (fraction) | 0.40 | 2/5 | Divide, then ×100 |
Calculate sale prices quickly:
Add sales tax to a purchase:
Find your test score percentage:
To find any percentage, break it into easy parts. For 35% of 200: Calculate 10% (20), multiply by 3 (60), add 5% (10) = 70!
Percentage change measures how much a value has grown or shrunk relative to its original value.
| Scenario | Original | New | Change |
|---|---|---|---|
| Stock price rise | $100 | $125 | +25% |
| Weight loss | 200 lbs | 180 lbs | -10% |
| Salary increase | $50,000 | $55,000 | +10% |
| Product discount | $80 | $60 | -25% |
A key concept: if something increases by 50% and then decreases by 50%, you don't end up back at the start!
This is why recovering from stock market losses is harder than it seems.
These are the six core percentage calculations used in business, finance, science, and everyday life × with the exact formula and a worked example for each:
| Calculation Type | Formula | Example |
|---|---|---|
| Percentage of a number | Result = (% × 100) × Number | 15% of 200 = 30 |
| What % is X of Y? | Result = (X × Y) × 100 | 30 is 15% of 200 |
| Percentage increase | Result = ((New - Old) × Old) × 100 | $80?$100 = +25% |
| Percentage decrease | Result = ((Old - New) × Old) × 100 | $100?$75 = -25% |
| Add % to a number | Result = Number × (1 + % × 100) | $200 + 20% = $240 |
| Remove % from a number | Result = Number × (1 - % × 100) | $200 - 20% = $160 |
Percentages show up everywhere — tips, discounts, grades and growth. Three quick examples:
Finding 15 percent of 80 (e.g. a 15% tip on an $80 bill).
Result: 15% × 80 = 12.
Expressing 45 as a percentage of 180 (e.g. a score of 45 out of 180).
Result: 45 ÷ 180 × 100 = 25%.
Adding a 30% increase to a base value of 250 (e.g. a price rising 30%).
Result: 250 × 1.30 = 325 (a 75-unit increase).
Subtract the old value from the new, divide by the old value, and multiply by 100. For example, 80 to 100 is (100−80) ÷ 80 × 100 = 25% increase.
Divide the part by the whole and multiply by 100. For example, 45 out of 180 is 45 ÷ 180 × 100 = 25%.
Multiply by 1 plus the percentage as a decimal. To add 30% to 250: 250 × 1.30 = 325.
To find the original before a known increase, divide by 1 plus the rate. If $325 already includes a 30% markup: 325 ÷ 1.30 = 250.