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Calculate percentages, increases, decreases, and discounts instantly.
💡 Tip: Leave a field empty to treat it as 0. This calculator runs entirely in your browser.
A percentage expresses a number as a fraction of 100. The word literally means "per hundred" — so 25% means 25 out of every 100, or one quarter. This calculator handles the four most common percentage calculations in one place, so you don't have to remember the formulas.
Multiply the whole by the percentage as a decimal. For example, to find 15% of 200: 200 × 0.15 = 30. Use this for tips, discounts, and tax calculations.
Divide the part by the whole and multiply by 100. For example, to find what percent 30 is of 200: (30 ÷ 200) × 100 = 15%. Use this to calculate test scores, market share, or completion rates.
Subtract the original from the new, divide by the original, and multiply by 100. For example, a price change from $100 to $125: ((125 − 100) ÷ 100) × 100 = 25% increase. Use this to measure growth, inflation, or salary changes.
Multiply by (1 + percentage/100) to add, or (1 − percentage/100) to subtract. For example, adding 15% tax to $80: 80 × 1.15 = $92. Use this for applying sales tax, VAT, or discounts.
The Percentage Calculator lets you figure out percentage calculatorinstantly, without reaching for a spreadsheet or doing the math by hand. Whether you're planning a budget, checking a loan, or working through homework, the tool applies the correct formula behind the scenes and shows the result the moment you enter your numbers.
Unlike a static chart or table, this calculator adapts to your exact inputs. You can adjust any value and see the outcome update in real time, which makes it easy to compare scenarios — for example, "what if the rate were 1% lower?" or "what if I paid an extra $50 a month?"
Common uses: people reach for this tool when they need to find a percentage increase and decrease calculator, what is x percent of y, percentage of total calculator, or percent change between two numbers.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The Percentage Calculator is based on the following formula:
part = ( percent / 100 ) × whole
Variables: part = Portion of the whole (same unit as whole) percent = Percentage rate (%) whole = Total or reference amount (currency, units, or count)
Finding "a percent of a number": convert the percent to a decimal and multiply by the whole. Reverse: percent = part / whole × 100.
Worked example: Step 1: What is 15% of $240? Convert: 15 / 100 = 0.15. Step 2: part = 0.15 × 240 = 36. Step 3: Reverse check: 36 / 240 × 100 = 15. Result: 15% of $240 is $36.
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