Percentage Calculator
MathFind X% of a number, what percent one number is of another, percentage change, or percentage difference, all in one calculator.
Percentage Amount
X% of the number
Increased by %
120.00
Number after % increase
Decreased by %
80.00
Number after % decrease
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Odeh Ahwal0people find this calculator helpful
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Calculator Stats
Creators
Odeh Ahwal0people find this calculator helpful
Views
Helpful
Saved
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This calculator handles four common percentage questions in one tool. Choose the mode that matches your question, and the fields below switch automatically: X% of a Number, What Percent is X of Y, Percentage Change, or Percentage Difference.
X% of a Number also shows the number after increasing or decreasing it by that percentage, in the same step, useful for quick discount or markup math. What Percent is X of Y answers questions like what percent 25 is of 200. Percentage Change tells you how much a value grew or shrank, as a percentage, from an old figure to a new one, useful for tracking price changes or performance over time. Percentage Difference compares two values symmetrically, useful when neither value is clearly the original one, such as comparing two competing prices or measurements.
The exact formula and a worked example for every mode, plus links to purpose-built percentage calculators for specific situations, are below.
X% of a number
Multiply the number by the percentage, then divide by 100. For example, 20% of 100: 100 times 20, divided by 100, equals 20. Increasing 100 by 20% gives 120, and decreasing it by 20% gives 80, both shown alongside the main result automatically, the same math behind a quick discount or markup. For a calculator built specifically around restaurant bills and tax, see the Tip Calculator.
What percent is X of Y
Divide the part by the whole, then multiply by 100. For example, 25 is what percent of 200: 25 divided by 200 equals 0.125, times 100 equals 12.5%.
Percentage change from old to new
Subtract the old value from the new value, divide by the old value, then multiply by 100. For example, going from 80 to 100: 100 minus 80 is 20, divided by 80 equals 0.25, times 100 equals a 25% increase. Going from 100 to 80 instead gives a negative 20% change, a decrease.
Percentage difference between two values
Percentage difference is different from percentage change. It compares two values symmetrically, using their average as the base, rather than treating one as the fixed starting point. Take the absolute value of the difference between the two numbers, divide by their average, then multiply by 100. For example, comparing 100 and 120: the difference is 20, the average is 110, and 20 divided by 110 times 100 equals about 18.18%.
This is useful when comparing two competing prices, measurements, or estimates where neither one is clearly the original value, unlike percentage change, which always measures relative to a specific starting point. If you're comparing a price with tax against one without, see the VAT Calculator instead, it handles that specific case directly.
Percentage calculators for specific situations
This calculator's four modes cover the general case. For a purpose-built version tailored to a specific situation, see:
- Discounts and Sale Prices, for the sale price and amount saved on a discount
- Tips (Restaurant), for a tip amount and total bill
- Grade / Test Scores, for a score from points earned out of points possible
- Commission Rates, for commission earned on a sale
- Tax Calculation, for tax owed on an amount
- Investment Gains/Losses, for the percentage return on an investment
- Business Growth (MoM/YoY), for month-over-month or year-over-year growth
- Body Weight Change, for percentage change in body weight over time
Frequently Asked Questions
How do I find X% of a number?
Set Mode to X% of a Number, enter the number, and enter the percentage. The result is the number multiplied by the percentage, divided by 100.
How do I calculate what percent one number is of another?
Set Mode to What Percent is X of Y, enter the part in the Part field and the whole in the Whole field. The result is the part divided by the whole, times 100.
How do I calculate percentage change from an old value to a new value?
Set Mode to Percentage Change, enter the starting figure as Old Value and the later figure as New Value. The result is positive for an increase and negative for a decrease.
What's the difference between percentage change and percentage difference?
Percentage change measures growth or decline relative to a specific starting value, so it can be positive or negative. Percentage difference compares two values symmetrically using their average, with no fixed starting point, and is always positive.
Can percentage change be negative?
Yes. A negative percentage change means the new value is lower than the old value, a decrease. A positive percentage change means an increase.
Why is percentage difference always a positive number?
Percentage difference uses the absolute value of the gap between the two numbers, divided by their average, so it always comes out positive regardless of which value is larger.
Can I use this to calculate a discount or a tip?
Yes, X% of a Number mode's Decreased by % result gives the price after a percentage discount directly. For a calculator built specifically for discounts or restaurant tips, with extra fields like sales tax and splitting the bill, see the dedicated Discount Calculator or Tip Calculator instead.
How do I increase or decrease a number by a percentage in one step?
Set Mode to X% of a Number. The Increased by % and Decreased by % results show both outcomes automatically, alongside the plain X% amount, without needing to calculate them separately.
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