Percentage calculator
Find a percent, a share, or a change, instantly.
25% of 80 = 20
If your two numbers are already percentages, this result is the relative change. A move from 20% to 25% is a 5 percentage point increase, but a 25% relative change.
- 3 calculation modes
- Formula shown with the result
- Percentage points explained
How to calculate a percentage
- Pick what you want to find.
- Type your two numbers.
- Read the result and the formula used.
Percentage formulas, with worked examples
Each mode of this calculator runs one of three formulas. Here they are with real numbers.
| Mode | Formula | Example |
|---|---|---|
| X% of Y | (X / 100) x Y | 12% of 450 = 54 |
| X is what % of Y | (X / Y) x 100 | 18 out of 24 = 75% |
| % increase | ((new - old) / old) x 100 | 80 to 92 = +15% |
| % decrease | Same formula, negative result | 250 to 200 = -20% |
Order matters in the change mode. It always divides by the starting number, so 80 to 92 is a 15% rise, while 92 back down to 80 is a drop of about 13.04%.
Percentage points or percent change?
When both numbers are already percentages, there are two correct ways to describe the gap. Percentage points are a plain subtraction. Percent change divides that gap by the starting rate.
| Change | Percentage points | Percent change |
|---|---|---|
| Mortgage rate 6% to 7.5% | +1.5 points | +25% |
| Unemployment 5% to 4% | -1 point | -20% |
| Sales tax 8% to 8.5% | +0.5 points | +6.25% |
| Interest rate 4% to 5% | +1 point | +25% |
Both numbers are true, they just answer different questions. A headline saying a rate "rose 25%" and one saying it "rose 1 point" can describe the same move from 4% to 5%, so check which one you are reading before comparing figures.
Mistakes that give the wrong percentage
- Expecting a rise and an equal fall to cancel out. 100 up 50% is 150, but 150 down 50% is 75, because the second change works on a bigger base.
- Assuming a loss needs the same percentage to recover. A price that drops 20%, from $100 to $80, needs a 25% rise to get back to $100.
- Swapping the numbers in the what percent mode. 18 is 75% of 24, but 24 is about 133.33% of 18.
- Dividing a change by the new number instead of the old one. For 80 to 92 that gives about 13.04% instead of 15%, and for 250 to 200 it gives -25% instead of -20%.
- Mixing up percent and percentage points when a rate changes, which can make a small move sound large or a large one sound small.
Doing percentages in your head
Move the decimal point one place to the left to get 10% of any number, then build from there. For a $42 bill, 10% is $4.20 and 5% is half of that, $2.10, so 15% is $6.30 and 20% is $8.40.
| Percent | Fraction | Decimal |
|---|---|---|
| 10% | 1/10 | 0.1 |
| 12.5% | 1/8 | 0.125 |
| 20% | 1/5 | 0.2 |
| 25% | 1/4 | 0.25 |
| About 33.33% | 1/3 | About 0.3333 |
| 50% | 1/2 | 0.5 |
| 75% | 3/4 | 0.75 |
Knowing these pairs turns many percentages into simple division. 25% of 360 is a quarter of it, 90, and 12.5% of 360 is an eighth, 45. Use the calculator when the percentage is awkward, like 17.5% or 6.25%.
Percentage calculator FAQ
What is 15% of 200?
15% of 200 is 30. The formula is (15 / 100) x 200 = 30.
20 is what percent of 50?
20 is 40% of 50. The formula is (20 / 50) x 100 = 40.
What is the percent change from 50 to 75?
That is a 50% increase. The formula is ((75 - 50) / 50) x 100 = 50.
What is the difference between percent and percentage points?
If a rate moves from 20% to 25%, that is a 5 percentage point increase, but a 25% relative increase, since (25 - 20) / 20 x 100 = 25.
Why is my percent change negative?
A negative result means the second number is smaller than the first, so it is a decrease rather than an increase.
What is 8% of 350?
8% of 350 is 28. The formula is (8 / 100) x 350 = 28.
45 is what percent of 180?
45 is 25% of 180. The formula is (45 / 180) x 100 = 25.
What is the percent change from 120 to 90?
That is a 25% decrease. The formula is ((90 - 120) / 120) x 100 = -25.