Percentage Calculator – パーセント計算機

6つのモードを備えたパーセント計算機：数値の割合、増減率、割引、チップ。入力と同時に結果表示、履歴付き。オフライン対応。

Percentage Calculator puts six everyday percent calculations one click away. Open the popup, pick a mode, type the numbers — the percentage calculator shows the answer live, while you type. No equals button, no page to load, no account. Everything runs locally, and the percentage calculator works offline. SIX MODES IN ONE PERCENTAGE CALCULATOR 🔢 What is X% of Y — the classic percent of a number question 📊 X is what percent of Y — turn two numbers into a percent 📈 Change from A to B — labelled clearly as growth or drop ➕ Increase or decrease a value by X% — price rises, salary raises, fees 🏷 Discount — enter price and percent off, see the final price and what you save 💵 Tip — bill, tip percent, split between people, settled in seconds WHY PEOPLE KEEP IT PINNED - Live results: the answer updates with every keystroke - Copy button next to every result — paste it into a chat, sheet or invoice - History of your last 10 calculations; click any entry to restore it - Clean money rounding: 49.99 with 20% off is 39.99, not 39.992000000001 - Friendly messages instead of NaN when an input makes no sense - Comma decimals like 12,5 are accepted alongside 12.5 - Works offline — the percentage calculator never touches the network HOW TO CALCULATE PERCENTAGE IN THREE STEPS 1. Click the toolbar icon to open the percentage calculator popup. 2. Choose a tab: percent of a number, percent change, discount, tip and more. 3. Enter your numbers and read the result instantly — press Copy if you need it elsewhere. EVERYDAY QUESTIONS IT ANSWERS 1. What is 20% of 150? The percent of a number mode answers 30 right away. 2. 30 is what percent of 200? Type both numbers, get 15%. 3. The price went from 80 to 120 — the percent change mode shows +50% growth. 4. A jacket costs 49.99 with 20% off — the discount mode shows 39.99 and your savings. 5. Dinner was 84.50, you tip 15% and split by 3 — everyone's share, calculated. WHAT MAKES THIS PERCENTAGE CALCULATOR DIFFERENT Most percent tools live on websites: you search, wait, close a cookie banner and only then type. This percentage calculator sits in your toolbar and opens instantly, with the last mode you used already selected. The result is large enough to read at a glance, every mode follows the same pattern, and the percentage calculator feels familiar no matter which tab you are on. FREQUENTLY ASKED QUESTIONS Q: Do I need an account or any setup? A: No. Install it, click the icon, and the percentage calculator is ready. Q: Does this percentage calculator work offline? A: Yes. Every mode runs locally in your browser. Nothing is sent anywhere, ever. Q: How do I calculate percentage increase between two values? A: Open the percent change tab, enter the start and end values, and the percentage calculator shows the signed change — growth appears with a plus sign, a drop with a minus. Q: Can it calculate percentage discounts with odd prices? A: Yes. The discount mode handles prices like 49.99 and rounds money to cents the way a receipt would. Q: Where is the history stored? A: On your device, in the extension's local storage. The percentage calculator does not collect or transmit any data. Q: What happens if I divide by zero? A: You get a plain-language explanation instead of an error code — for example, that a percent change from zero is undefined. Q: Can I reuse an old calculation? A: Yes. Click any entry in the history list and the percentage calculator restores the mode and the numbers. BUILT FOR QUICK, REPEATED USE A percentage calculator is something you reach for ten times a day: a sale price at checkout, a percent change in a report, a tip after dinner, a quick percent of a number while budgeting. This extension keeps all six calculations behind one icon, remembers your last mode, and answers while you type. The interface stays out of the way: tabs, two or three fields, a large result and a Copy button. If you regularly work with percent values for work, shopping or study, this percentage calculator turns each of those moments into a two-second task — no search engine, no spreadsheet, no mental math under pressure. Install Percentage Calculator and let every percent question answer itself the moment you type the numbers.