💯 Percentage Calculator
Solve any percentage problem: of, change, increase, decrease. Useful for shoppers, students and business owners. Free, unlimited, private — works entirely in your browser.
How to use
- Pick your calculation type: X% of Y, percentage change, increase, or decrease.
- Enter the two numbers — for example 20 and 150 to find 20% of 150.
- The answer appears instantly as you type; no button needed.
- Use the result in your shopping, grading, or budgeting — everything stays in your browser.
FAQ
Is it really free?
Yes — every tool on this site is 100% free with no limits, no signup and no watermarks.
Is my data private?
Absolutely. All processing happens locally in your browser. Your files are never uploaded to any server.
How do I calculate a discount price?
Choose the decrease mode, enter the original price and the discount percent. The tool shows the discount amount and the final price. Example: 25% off a $80 item = $20 off, final price $60.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 45 out of 60 is (45 ÷ 60) × 100 = 75%. Use the percentage-change mode to do this automatically.
How do I calculate a salary raise?
Use the increase mode: enter your current salary and the raise percent. A 10% raise on $50,000 gives $5,000 more, for a new salary of $55,000.
Why do successive discounts not add up?
Because each discount applies to a shrinking base. A 20% discount followed by 10% off is not 30% off — it's 1 − (0.80 × 0.90) = 28% off. Our calculator handles each step so you see the true final price.
Percentage Calculator — Complete Guide
Percentages show up everywhere: sale tags, exam scores, tax rates, tips, interest, and salary negotiations. A Percentage Calculator removes the mental arithmetic so you get exact answers in seconds — and understanding the few core formulas makes you faster even without the tool.
The three core formulas
- X% of Y: (X ÷ 100) × Y. Example: 15% of 200 = 0.15 × 200 = 30.
- What percent is A of B: (A ÷ B) × 100. Example: 30 is what percent of 200? (30 ÷ 200) × 100 = 15%.
- Percentage change: ((New − Old) ÷ Old) × 100. A price rising from $50 to $65 is a 30% increase.
Everyday use cases
- Shopping: verify that the "70% off" tag really gives the advertised price — retailers sometimes inflate the original.
- Grades: convert raw marks to percentages and work out what you need on the final to hit your target.
- Finance: compare interest rates, compute tax, and sanity-check investment returns.
- Business: calculate margins, markups, and year-over-year growth for reports.
Common traps
- Percentage points vs. percent: a rate rising from 5% to 7% is a 2-percentage-point rise, but a 40% relative increase. Politicians and advertisers mix these up — now you won't.
- Compounding: a 10% gain followed by a 10% loss doesn't return you to start: $100 → $110 → $99. Losses hurt more than equal gains help.
- Base confusion: "50% more" and "50% off" are not symmetric. Always ask: percent of what?
Pro tips
For quick mental math, remember 10% is just moving the decimal point one place: 10% of 240 is 24, so 5% is 12 and 15% is 36. For tips, compute 10% and double it for 20%. And when a store stacks coupons, multiply the remaining fractions (0.8 × 0.9) rather than adding the percents.
Reverse percentages
Sometimes you know the result and need the original. If a $68 bill includes 15% tax, the pre-tax price is 68 ÷ 1.15 = $59.13. If your investment grew 40% to $7,000, it started at 7,000 ÷ 1.40 = $5,000. Dividing by (1 + rate) reverses any percentage increase; dividing by (1 − rate) reverses a decrease.
📖 Step-by-step tutorial
New to this tool? Read our step-by-step guide to solving percentage problems online — with worked examples and practical tips.