Percentage Calculator
Calculate percentages instantly: find X% of a number, or what percentage one number is of another.
Táto kalkulačka zatiaľ nebola preložena do jazyka Slovenčina.
Zatiaľ zobrazujeme verzi v jazyce Angličtina, ako dokončíme preklad.
What is X% of Y?
%
of
Result
30
X is what % of Y?
out of
Result
15%
Percentage calculator. Find X% of a number, and what percent one number is of another.
This percentage calculator does two things: it finds X% of a number, and it finds what percent one number is of another. Enter your numbers in either mode to get the result rounded to two decimal places.
What Is a Percentage?
A percentage is a fraction of 100: 25% means 25 out of every 100, which is the same as one quarter. The word comes from the Latin per centum, “per hundred,” and the % sign is shorthand for that same relationship to 100.
Nearly every percentage question in daily life is one of two types, and this calculator is built for both. The first is “what is X% of a number” — the math behind a 7% sales tax (7% of 1,500 is 105), a 30% markdown (30% of 1,200 is 360), or a 15% tip. The second is “X is what percent of a number” — the math behind a test score (45 out of 180 is 25%) or one branch's share of total sales (350 out of 2,000 is 17.5%). The two modes are mirror images of each other: 7% of 1,500 is 105, and 105 out of 1,500 is 7%.
There is deliberately no separate “percentage change” mode. That calculation is still simple to do here — subtract the old value from the new value yourself, then run that difference through the second mode against the old value (the FAQ below walks through a full example). Keeping the tool to two clear operations means fewer mixed-up inputs and a quicker answer.
How to Use the Percentage Calculator
The calculator is split into two modes, one above the other. Pick the mode that matches your question, type in your two numbers, and the answer appears as you go — there is no button to press.
Mode 1 — What is X% of Y?
1. Enter the percentage (X), for example 7 for a 7% sales tax.
2. Enter the base number (Y), for example 1,500.
3. The calculator multiplies Y by X and divides by 100, so 1,500 × 7 ÷ 100 = 105.
Mode 2 — X is what percent of Y?
1. Enter the part (X), for example a score of 45.
2. Enter the whole (Y), for example a maximum of 180.
3. The calculator divides X by Y and multiplies by 100, so 45 ÷ 180 × 100 = 25%.
Both modes round to two decimal places, so 17 out of 60 shows as 28.33%, not a clean 28%. A fast way to check your work is to flip between the modes: if Mode 1 says 7% of 1,500 is 105, then entering 105 and 1,500 in Mode 2 should return 7%.
Percentage Formulas
- = The percentage value (for example, 20 for 20%)
- = The base number you are taking a percentage of
The formula above answers Mode 1, "What is X% of Y?" Mode 2, "X is what percent of Y?", rearranges the same relationship to solve for the rate instead:
Both are the same idea seen from two directions — a part, a whole, and a rate scaled to 100. Fix any two of them and the third follows. Percentage change is not a third formula wired into the tool, but it reuses Mode 2: take the difference between the new and old values, then find what percent that difference is of the old value:
A positive result is an increase and a negative result is a decrease. To run it through this calculator, work out the numerator yourself, then enter it as the part and the old value as the whole in Mode 2.
Common Percentage Calculations in Both Modes
| Question | How it's calculated | Result |
|---|---|---|
| 15% of 200 (tip) | 200 × 15 ÷ 100 | 30 |
| 7% of 1,500 (sales tax) | 1,500 × 7 ÷ 100 | 105 |
| 20% of 850 (commission) | 850 × 20 ÷ 100 | 170 |
| 30% of 1,200 (discount) | 1,200 × 30 ÷ 100 | 360 |
| 33% of 250 | 250 × 33 ÷ 100 | 82.5 |
| 45 out of 180 (test score) | 45 ÷ 180 × 100 | 25% |
| 105 out of 1,500 (tax rate) | 105 ÷ 1,500 × 100 | 7% |
| 350 out of 2,000 (share of sales) | 350 ÷ 2,000 × 100 | 17.5% |
| 17 out of 60 (quiz score) | 17 ÷ 60 × 100 | 28.33% |
Percentage Calculation Examples
Sales Tax Both Ways: 7% of $1,500 and Back Again
Say a purchase comes to $1,500 before tax and the local sales-tax rate is 7%. Use Mode 1: 7% of 1,500 is 105, so the tax adds $105. Now flip it around — if you see $105 of tax on a $1,500 subtotal and want to confirm the rate, use Mode 2: 105 out of 1,500 is 7%. The same pair of numbers read from both sides is exactly what the two modes are for.
How Much You Save on a 30% Markdown
A $1,200 item is marked 30% off and you want the dollar amount of the discount. Use Mode 1: 30% of 1,200 is 360, so you save $360. This calculator returns the discount amount; to get the price you actually pay, subtract that from the original price. If you are comparing several stores or stacking coupons, a dedicated discount calculator handles that more directly.
Turning a Test Score Into a Percentage
You got 45 questions right out of 180 and want your percentage score. Use Mode 2: 45 ÷ 180 × 100 = 25%. The same method fits any raw score — 17 correct out of 60 comes to 28.33%, which the calculator rounds to two decimals rather than a tidy 28%. Keep in mind this figure is the proportion you got right, not a letter grade; grading scales vary from one school to the next.
Commission, Fees, and Shares of a Total
Percentages run through everyday money math in both modes. A 15% commission on a $200 sale is Mode 1: 15% of 200 is 30. A 20% platform fee on an $850 payout is 20% of 850, or 170. Going the other way, if one location brought in $350 of a $2,000 team total, Mode 2 shows 350 ÷ 2,000 × 100 = 17.5% of sales. And a 33% cut of a $250 bonus pool is 33% of 250, which comes to 82.5.
Common Percentage Mistakes to Avoid
- Swapping the part and the whole in Mode 2. "45 is what percent of 180" (25%) is not the same as "180 is what percent of 45." The number you scored goes on top and the number possible goes on the bottom — always the part divided by the whole.
- Confusing percent with percentage points. If a rate rises from 3% to 5%, that is a 2 percentage-point increase, not a 2% increase. Measured against the starting 3%, the relative jump is much larger. News and finance headlines mix these up constantly.
- Forgetting to divide by 100. Finding X% of a number always includes the ÷ 100 step: 7% of 1,500 is 1,500 × 7 ÷ 100 = 105, not 10,500. When you are finding a percent in Mode 2 instead, the × 100 comes at the very end.
- Using the wrong base for a change. When you work out a percentage change through Mode 2, divide by the old (starting) value, never the new one. Using the new value as the base gives a different — and wrong — percentage.
- Assuming stacked discounts add up. 30% off followed by 20% off is not 50% off, because the second cut applies to the already-reduced price. Percentages taken from different bases cannot simply be added together.
Tips for Working With Percentages
- Check your answer with the opposite mode. If Mode 1 says 7% of 1,500 is 105, then entering 105 and 1,500 in Mode 2 must give 7% back. If it doesn't, you typed the numbers into the wrong boxes.
- Use the 10% trick for mental math. Find 10% by moving the decimal point one place left, then scale it: for 30% of a number, take 10% and multiply by three; for 15%, take 10% plus half of it.
- Percentages are reversible, so pick the easier direction. X% of Y always equals Y% of X. 15% of 200 is 30, and 200% of 15 is also 30 — compute whichever side is simpler in your head.
- Expect the two-decimal rounding. The calculator rounds to two places, so 17 out of 60 shows as 28.33% rather than an endless 28.333…. For money that will be invoiced, allow for a fraction of a cent.
- Percentages over 100% are normal. Whenever the part is bigger than the whole, Mode 2 returns more than 100% — for example a figure that grew past its starting point. It is not an error.
- A percentage only means something next to a benchmark. 25% is a poor exam score but an unusually large pay raise, since a typical annual raise is only a few percent. Compare your number to a sensible reference before you act on it.
Frequently Asked Questions About Percentages
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 45 out of 180 is 45 ÷ 180 × 100 = 25%. In this calculator that is Mode 2, where the part goes in the first box and the whole in the second.
How do I find X% of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. That is Mode 1 of the calculator: enter the percent first, then the base number.
How do I calculate a percentage increase or decrease with this calculator?
This calculator has no dedicated percentage-change mode, but you can still get one in two steps. First subtract the old value from the new value yourself. Then enter that difference as the part and the old value as the whole in Mode 2. For example, if a monthly plan rose from $2,000 to $2,350, the increase is $350; entering 350 and 2,000 in Mode 2 gives 350 ÷ 2,000 × 100 = 17.5%. Always divide by the old value, not the new one.
Is 20% of 50 the same as 50% of 20?
Yes — both equal 10, and the rule holds for any pair. X% of Y always equals Y% of X because you are multiplying the same two numbers either way. In Mode 1, 15% of 200 is 30, and 200% of 15 is also 30, so flip to whichever direction is easier to compute.
What is the difference between percent and percentage points?
Percentage points measure the plain arithmetic gap between two percentages, while a percent measures relative change. If a rate goes from 3% to 5%, that is a 2 percentage-point rise but a much larger increase relative to the starting 3%. The distinction matters a lot in finance and news reporting.
Can a percentage be more than 100%?
Yes. A percentage above 100% simply means the part is larger than the whole it is compared to. If sales grew from 20 units to 50 units, the new figure is 250% of the old one. Percentages over 100% are common in growth, comparisons, and investment returns.
How do I convert a percentage to a decimal or a fraction?
To turn a percentage into a decimal, divide by 100, so 25% becomes 0.25. To make it a fraction, put the number over 100 and simplify: 25% is 25/100, which reduces to 1/4. To go from a decimal back to a percentage, multiply by 100.
How do I find the original price before a discount?
This is reverse math rather than one of the two modes, but it is quick. Divide the price you paid by (1 minus the discount as a decimal). If you paid $68 after 15% off, the original was 68 ÷ 0.85 = $80, because $68 is 85% of the original price.
Is this percentage calculator free to use?
Yes, it is completely free, with nothing to install and no limit on how many calculations you run. It works in any browser on a phone, tablet, or computer, and the result updates the moment you type a number into either mode.
How accurate are the results, and how are they rounded?
The calculator uses the standard percentage formulas and rounds every result to two decimal places, so 17 out of 60 shows as 28.33%. Values that divide evenly, like 45 out of 180 = 25%, show with no extra digits. For invoices or tax filings, double-check against the official rate that applies to you.
I got my percentage — how do I know if it is good or bad?
It depends entirely on context, so compare the number to a benchmark for that situation. A 25% score on an exam is low, but a 25% pay raise is exceptional when a typical annual raise is only a few percent. The same percentage can be great news or bad news depending on what it measures.