To find a percentage of a number, multiply the number by the percentage and divide by 100. So 8% of 250 is 20, because 250 × 8 ÷ 100 = 20.
The calculator does that as you type. It also gives two more answers. One is the number minus the percentage; the other is the first entry as a percent of the second.
Which percentage question are you asking?
Most percentage problems come in one of three shapes. The same two numbers can need a different sum in each, so name yours first.
The headline result answers the first question. For the second, type the part in the Percentage box and the whole in the Of value box. Ignore the % sign this once, and read "The first as a share of the second". With 18 and 225, it shows 8.0%, because 18 is 8% of 225.
The third needs a start, an end and a direction. The percentage return calculator takes those two values and gives the change in percent.
Adding a percentage or taking one off
To take 12% off 450, work out 12% of 450, which is 54, and subtract it. That leaves 396. The calculator shows this as "The remaining share", so you can skip the subtraction.
To add 12% instead, put the 54 back on top: 450 + 54 = 504. A multiplier does either job in one step. Multiply by 1.12 to add 12%, or by 0.88 to remove it.
The multiplier habit pays off once percentages come in a chain. For shop prices, the percent off calculator gives the sale price and your saving directly.
Getting back to the number you started with
Say a 5% raise took your salary to $63,000. What was it before? The tempting move is to take 5% off $63,000, which gives $59,850. That's wrong.
The raise was 5% of the old salary, not of the new one. So you divide by 1.05 instead of subtracting:
Subtracting was out by $150 here, and the error grows with the percentage. The same division strips tax out of a price that includes it: divide by one plus the tax rate.
Discounts work in reverse. A jacket that's $60 after 25% off didn't cost $75 before. It cost 60 ÷ 0.75 = $80.
Why a 10% rise and a 10% fall don't cancel
Each percentage is taken from a different base. The fall comes off the bigger, raised number, so it removes more than the rise added. Here's where 100 ends up after a rise and an equal fall:
| Rise, then fall by | Value after the rise | Size of the fall | Where 100 ends up |
|---|---|---|---|
| 5% | 105 | 5.25 | 99.75 |
| 10% | 110 | 11 | 99 |
| 25% | 125 | 31.25 | 93.75 |
| 50% | 150 | 75 | 75 |
The shortfall, as a share of the start, is the percentage squared. So 10% of 10% is 1%, and 50% of 50% is 25%. Small swings barely register, but large ones leave a real gap. After a 50% fall, you'd need a 100% gain just to get back to where you began.
The starting point decides the percent change
The U.S. Bureau of Labor Statistics (BLS) makes this point in the technical note to its Consumer Price Index release. In its example, two price indexes both rise by 18 points. One climbs from 225 to 243, the other from 110 to 128.
The first rise works out at 8.0%, the second at 16.4%. It's about twice as large because it starts from a lower level. That's why the BLS reports moves as percent changes. Point changes, it explains, "are affected by the level of the index."
A change quoted in raw units needs the same care. A $20 price rise means little until you know the starting price. For two index readings, the CPI inflation calculator turns them into a percent change.
Percentage points aren't the same as percent
When a rate itself moves, you can describe the move in two ways. Percentage points are the plain gap between the old rate and the new one. Percent is that gap divided by the old rate.
On September 17, 2025, the Federal Reserve cut its federal funds target range "by 1/4 percentage point." The top of the range fell from 4.50% to 4.25%. Measured in percent, that's a cut of about 5.6%.
| What changed | From (%) | To (%) | Change in points | Change in percent |
|---|---|---|---|---|
| Fed funds target, top of range (Sept. 2025) | 4.50 | 4.25 | −0.25 | −5.56% |
| Labor force participation rate (Jan. to Aug. 2026) | 62.10 | 61.60 | −0.50 | −0.81% |
| Monthly CPI change (July to Aug. 2026) | 0.10 | 0.40 | 0.30 | 300.0% |
Both columns are correct, which is how headlines can mislead. The BLS reported a 0.4% rise in consumer prices for August 2026, after 0.1% in July. Calling that a 300% jump is right on paper. Yet the monthly pace moved by just 0.3 of a point.
Small moves in rates are often counted in basis points. The SEC's Investor.gov defines a basis point as one hundredth of a percentage point. So the Fed's quarter-point cut was 25 basis points. The basis point calculator shows what a given number of them means in dollars.
A shortcut for awkward percentages
X% of Y always equals Y% of X, because both are X × Y ÷ 100. That lets you swap a hard sum for an easy one. Working out 4% of 75 in your head is fiddly, but 75% of 4 is plainly 3.
For round figures, start from 10% by moving the decimal point one place left. So 10% of 380 is 38, 5% is half that, 19, and 15% is the sum, 57.
Sources
- U.S. Bureau of Labor Statistics, Consumer Price Index – August 2026, with technical note (September 11, 2026)
- U.S. Bureau of Labor Statistics, The Employment Situation – August 2026 (September 4, 2026)
- Federal Reserve, FOMC statement (September 17, 2025)
- U.S. Securities and Exchange Commission, Investor.gov Glossary: Basis Point