Percentage Calculator

Type in a percent question and most calculators just fire back a number. You either trust it or you retype everything to check. But percentages almost never go wrong at the arithmetic. Dividing by 100 is easy. They go wrong at the setup, when you pick the wrong number as the base, and a bare answer hides exactly that mistake, which is why the working stays on screen here. Every line of arithmetic sits right under the answer, so you can see how it framed your numbers and catch a bad setup before it costs you a refund or a grade.

It handles the six percentage questions that actually come up. What is X% of Y (tips, tax, discounts). X is what percent of Y (a score, a share of a budget). X is P% of what number, run backward to recover a total. Increase or decrease a value by a percent. Percentage change from one figure to another. And percentage difference, for two numbers where neither is the obvious starting point. Pick an operation, type two numbers, and the answer lands the moment you stop typing. No Calculate button, no reload.

Two things here most free calculators skip. Each of the six operations keeps its own set of numbers, so you can flip between "what percent" and "find the total" to sanity-check a figure without retyping a thing. And Copy link builds a URL that reopens this exact calculation, inputs and all, handy for bookmarking a sum or sending someone the exact number you got. Copy result drops the answer and its steps onto your clipboard.

Everything runs in your browser. Nothing you type is uploaded, and there's no sign-up. Share is the one place your numbers travel, and even there they sit after the # in the link, the part a browser never sends to a server. Leave a box empty or type something that isn't a number and you get a short prompt, not a jarring "NaN", and the divide-by-zero cases are caught and explained rather than left to break.

1. Pick an operation from the row of buttons: percent of a number, what percent, find the total, add or subtract a percent, percentage change, or percentage difference. The line under the buttons spells out the exact question each one answers.
2. Type your two numbers into the labeled boxes. The labels rename themselves to match the operation, so you always know which value belongs where. Decimals and negatives are fine.
3. Read the answer in the box below, written as a full sentence, with the worked steps listed underneath. Follow the steps to confirm the tool set your problem up the way you meant it.
4. Copy what you need. Copy result puts the answer plus its steps on the clipboard. Copy link saves a URL that reopens this exact calculation later.
5. Switch operations without losing your place. Each one remembers its own numbers, and the tool holds your last inputs for the next visit.

Ask people what makes percentages hard and they'll say the math. It isn't. The math is one operation. What trips people is deciding which number is the base, the number you're taking the percentage of, and getting that wrong quietly produces a confident, wrong answer.

The classic is the sale-price trap. You paid $84 for something after 30% off, and you want the original price. The instinct is to add 30% back: 84 × 1.30 = $109.20, but that gives the wrong answer. The 30% came off the original, not off the $84 you paid, so you're adding a percentage of the wrong number. Work from what you actually paid instead. After 30% off you paid 70% of the original, so $84 is 70% of the price you're looking for. That's a "find the total" problem: 84 ÷ 0.70 = $120. Check it, 30% off $120 is a $36 cut, and 120 - 36 = 84. It holds.

The same move strips tax back out of a receipt (divide a total by 1.08 to undo 8% tax) or recovers a salary before a raise. Any time a number already has a percentage baked into it and you want the "before" figure, you divide by the fraction that's left. You never add the percentage back on. The "find the total" operation does this directly, and its steps show the division so you can watch it dividing rather than adding.

One more that costs shoppers money: stacked discounts don't add. "30% off, then an extra 20% with a code" is not 50% off. The second cut lands on what's left after the first, so you keep 0.70 × 0.80 = 0.56 of the price, a 44% discount, not 50. Discounts multiply on a shrinking base rather than stacking.

Almost every percentage problem is the same equation with a different piece missing:

part = whole × (percent ÷ 100)

Know the percent and the whole, multiply, and you've found the part (what is 15% of 200). Know the part and the whole, divide and scale up, and you've found the percent (30 is what percent of 200). Know the part and the percent, divide, and you've recovered the whole (that's the reverse trick above). Spotting which piece you're missing is really the only skill. Once you see that, the "six calculations" collapse into one.

Percentage change behaves differently, because it measures movement from a starting point: (new - old) ÷ old × 100, always divided by the old value. Going 200 to 230 is a 15% increase, and the tool colors the direction. Change is a deep topic on its own. It isn't symmetric (a 50% loss needs a 100% gain to recover), and it's easy to divide by the wrong figure, so it gets a dedicated percentage change calculator with its own worked examples. Percentage difference is the cousin for two numbers with no natural "before". It divides the gap by their average and always comes out positive, so the order you list them in doesn't matter.

X% of Y always equals Y% of X. It's exact, because both sides work out to X × Y ÷ 100. So an ugly sum flips into an easy one. 4% of 75 looks fiddly, but 75% of 4 is plainly 3. When one of your numbers is friendly (25, 50, a round hundred), swap the percent and the value and let it do the work.