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Percentage Calculator

Calculate the Percentage increase/decrease

What is the % increase/decrease
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What is X% of Y?

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X is what % of Y?

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Add X% to Y

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Subtract X% from Y

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To use this Percentage Calculator, just input your figures to calculate the following:

  • Percentage increase/decrease
  • What is X% of Y?
  • X is what % of Y?
  • Add X% to Y
  • Subtract X% from Y

Do you have a calculation where you are trying to figure out how much a product is going to cost with tax added? Go to the “Add X% to Y” window and input your numbers.

Let’s say you’re buying a laptop computer for £349.99 (Y) and the sales tax on top of that is 12% (X). Your calculation would look like this:

12% + £349.99 The Percentage Calculator instantly answers with £391.9888

It couldn’t be any easier than that!

Bookmark this page so you can easily refer to it whenever you require a percentage calculation and don’t have a calculator handy.


Percentage Increase/Decrease Calculation

Example: What is the percentage increase from 16 to 25

Equation ( ( 25 – 16 ) ÷ 16 ) * 100 = 56.25%

Equation Breakdown

  1. 25 – 16 = 9 ( Find the difference between X and Y )
  2. 9 ÷ 16 = 0.5625 ( Divide the difference by X to calculate the percentage represented by a decimal )
  3. 0.5625 * 100 = 56.25% ( Multiple the result by 100 to get a nicely formatted percentage)

What is X% of Y? Calculation

Example: What is 20% of 250

Equation ( 20 ÷ 100 ) * 250 = 20%

Equation Breakdown

  1. 20 ÷ 100 = 0.2 ( convert 20% to a decimal )
  2. 0.2 * 250 = 20% ( multiple the decimal by the total to calculate the percentage )

X is what % of Y? Calculation

Example: 30 is what percentage of 125

Equation ( 30 ÷ 125 ) * 100 = 24%

Equation Breakdown

  1. 30 ÷ 125 = 0.24 ( divide 30 by 125 to calculate the percentage as a decimal )
  2. 0.24 * 100 = 24% ( multiple the result by 100 to get a nicely formatted percentage )

Add X% to Y Calculation

Example: Add 12.5% to 120

Equation 120 + ( 120 * ( 12.5 ÷ 100 ) ) = 135

Equation Breakdown

  1. 12.5 ÷ 100 = 0.125 ( convert percentage to a decimal )
  2. 120 * 0.125 = 15 ( calculate the increase by multiplying 120 by the decimal )
  3. 120 + 15 = 135 ( add the increase )

Subtract X% from Y Calculation

Example: Subtract 17.5% from 120.

Equation 120 - ( 120 * ( 17.5 ÷ 100 ) ) = 99.

Equation Breakdown

  1. 17.5 ÷ 100 = 0.175 ( convert percentage to a decimal )
  2. 120 * 0.175 = 21 ( calculate the increase by multiplying 120 by the decimal )
  3. 120 - 21 = 99 ( subtract the increase from 120 to calculate the result )

The History of Percentages

Ugh, maths, right? Well, believe it or not, the world around us is surrounded by percentages. You’ve seen and heard the phrases all the time. Save 10% today only on all our new stock! Buy one at full price and get another one at half price! Get one at £2.50 or buy 3 for £6.00! You can’t get away from this fractional type of maths even if you wanted to. But what is the deal about percentages? Before we get into how you can easily figure them out with this online tool, here is a little bit of history about this useful form of calculating everything from taxes to discounts.

That’s a fact. In Ancient Rome, fractions were often used in calculations. For example, the fractions used at the time were often multiples of 100. The Romans were some of the first people to pay a taxes on goods they purchased. It was Augustus who placed a levy of 1/100th on anything sold at auction. This became known as the centesima rerum venalium. Looking back on it now, it is easy to see that these types of calculations – based on multiples of 100 – were the equivalent of computing percentages in modern times.

In the Middle Ages currency denominations grew and the need to compute fractions with a denominator of 100 became the norm. It was so widely used at this time that by the late 15th century and into the early 16th century published math texts commonly used it for computations. To give you an idea of how these math equations were used, the texts focused on such calculations as methods to figure out profit and loss as well as for calculating interest rates. Once the 17th century arrived, interest rates were quoted in hundredths as the standard.

We all know the term ‘percent’ but the history of it is also quite interesting. It originates from the Latin term per centum, which translates to mean “by the hundred.” Do you sense a theme developing here? Well, per centum evolved from an old Italian term that stood for “for a hundred.” That term was per cento. Over time the “per” part of the term got shortened to just the letter “p” and soon disappeared. The cento part of the term remained but was also abbreviated down to “o o” which also evolved to the symbol we all recognise - %.

Percentage Fun Facts

In Sports, They Use It Incorrectly

It appears to be common in modern times to see ancient, established terms used in more than one way. Sometimes those terms are also used incorrectly. Sports statistics are a form of maths and for those fanatics who pour over win/loss numbers will also encounter team percentages. However, in sports stats the number being referenced is not a percentage and is written as a decimal proportion. An example is a football team that has a .500 winning percentage. In other words, the team has won 50% of their games not 0.500% of them. Confused yet?

Oh, But It Gets Even Stranger

You’ve seen the highway warning signs as you approach a steep downhill section of the road you are travelling on. The steepness of the slope of that road is expressed in the form of a percentage. Maybe the sign says 12%. The formula used in this case is 100 x the rise/run. It could also be described as the tangent of the inclination angle x 100. What it actually means is the percentage referred to as a grade is the ratio of vertical and horizontal distances vehicles would travel going up or downhill but expressed as a percent figure. So how does that compute?