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Percentage Calculator
Six percentage calculators in one. Type in any box and the answer updates instantly, with the formula shown so you can check the math.
Instant resultsFormulas shownRuns in your browser
1Percent of a number
What is % of ?
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2What percent is X of Y
is what % of ?
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3Percentage change
From to
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4Increase or decrease by a percent
by %
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5Reverse percentage
is % of what?
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6Discount & sales tax
Price with % off, plus % tax
You pay
—
You save
—
Tax
—
How to calculate percentages
A percentage is a number expressed as a fraction of 100. “Per cent” literally means “per hundred”, so 25% is 25/100 or 0.25. Every calculator above is built on that one idea:
- X% of Y = Y × X ÷ 100. Useful for tips, commissions and interest.
- X is what % of Y = X ÷ Y × 100. Use it for test scores, budgets and conversion rates.
- Percentage change = (new − old) ÷ |old| × 100. Positive is an increase, negative a decrease.
- Increase Y by X% = Y × (1 + X ÷ 100); decrease uses (1 − X ÷ 100).
- Reverse percentage = part ÷ (X ÷ 100). Find the whole when you know a part and its percentage.
A common trap
A 50% increase followed by a 50% decrease does not bring you back to where you started: 100 → 150 → 75. Each percentage applies to a different base. That's why a stock that drops 50% needs to rise 100% to recover.
FAQ
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 80 is 80 × 15 ÷ 100 = 12.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 50 to 65 is (65 − 50) ÷ 50 × 100 = a 30% increase.
What is the difference between percentage change and percentage points?
Percentage points measure the simple difference between two percentages (5% to 7% is +2 points), while percentage change is relative (5% to 7% is a 40% increase).
How do I find the original price before a discount?
Divide the sale price by (1 − discount ÷ 100). A $60 item after a 25% discount originally cost 60 ÷ 0.75 = $80. Use the reverse percentage calculator (number 5) with 75% for this.
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