Percentage Calculator
Calculate percentages instantly — find % of a number, % change, or what % one number is of another.
Result
20% of 500 = 100
Common percentages of 500
How to use this percentage calculator
This percentage calculator has three modes to cover every common percentage problem. % of numberanswers “what is 20% of 500?” — enter the percentage and the number to get the result instantly. % change calculates the percentage increase or decrease between two values — useful for tracking price changes, growth rates, or comparing metrics.
X is what % of Y works in reverse: enter two numbers to find what percentage the first is of the second. This is useful for calculating test scores, discount rates, or any situation where you need to express one number as a fraction of another.
All calculations update in real time as you type. Use the copy button to grab the result for use in another app or spreadsheet.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100. Formula: Result = (Percentage ÷ 100) × Number. For example, 20% of 500 = (20 ÷ 100) × 500 = 0.20 × 500 = 100. A quick shortcut: to find 10%, move the decimal point one place left. To find 20%, double the 10% result. To find 25%, divide by 4.
How do I calculate percentage change?
Percentage change = ((New Value − Original Value) ÷ |Original Value|) × 100. For example, from 200 to 250: ((250 − 200) ÷ 200) × 100 = (50 ÷ 200) × 100 = 25% increase. If the result is positive it's an increase; negative means a decrease. Always divide by the absolute value of the original to handle negative starting values correctly.
What is the percentage difference between two numbers?
Percentage difference measures the relative difference between two values without a defined 'original'. Formula: |V1 − V2| ÷ ((V1 + V2) ÷ 2) × 100. For example, the percentage difference between 40 and 60 = |40 − 60| ÷ ((40 + 60) ÷ 2) × 100 = 20 ÷ 50 × 100 = 40%. This is different from percentage change, which requires a defined starting point.
How do I calculate what percentage one number is of another?
Divide the first number by the second, then multiply by 100. Formula: (X ÷ Y) × 100 = X as a % of Y. For example, 75 is what % of 300? (75 ÷ 300) × 100 = 0.25 × 100 = 25%. This is useful for calculating test scores (marks out of total), discount rates (discount amount ÷ original price), or market share (your value ÷ total market).
How do I calculate a percentage increase?
Percentage increase = ((New − Original) ÷ Original) × 100, where New > Original. Example: a salary raised from $60,000 to $66,000 = ((66,000 − 60,000) ÷ 60,000) × 100 = (6,000 ÷ 60,000) × 100 = 10% increase. To find the new value after a percentage increase: New = Original × (1 + Percentage ÷ 100). So a 10% increase on $60,000 = $60,000 × 1.10 = $66,000.
How do I calculate a percentage decrease?
Percentage decrease = ((Original − New) ÷ Original) × 100, where Original > New. Example: a price drops from $80 to $60 = ((80 − 60) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% decrease. To find the new value after a percentage decrease: New = Original × (1 − Percentage ÷ 100). A 25% decrease on $80 = $80 × 0.75 = $60. Note: a 50% increase followed by a 50% decrease does not return to the original value.
What is the formula for percentage?
The core percentage formula is: Percentage = (Part ÷ Whole) × 100. From this you can derive all other percentage formulas: (1) Finding the part: Part = (Percentage ÷ 100) × Whole. (2) Finding the whole: Whole = Part ÷ (Percentage ÷ 100). (3) Percentage change: ((New − Old) ÷ |Old|) × 100. (4) Reversing a percentage increase: if a value increased by X%, the original = New ÷ (1 + X/100). These four formulas cover virtually every percentage problem you'll encounter.
How do I calculate percentage in my head quickly?
Several mental shortcuts make percentage arithmetic fast: 10% = divide by 10 (move decimal left). 1% = divide by 100. 5% = halve the 10% result. 20% = double the 10% result. 25% = divide by 4. 50% = divide by 2. 75% = three-quarters (halve, then add to half). For non-round percentages, break them down: 17% = 10% + 5% + 2%. For percentage of a large number, round to the nearest easy number first, then adjust. For example, 19% of $53 ≈ 20% of $50 = $10, then subtract a small adjustment.