Skip to main content
- Smaller Text | + Larger Text

Percentage Calculator: Free Online Instant Calculation

Printer icon
  • Synopsis: Published: 2013-12-12 (Rev. 2016-05-30) - Free online instant calculator for finding a percentage of a number as well as reverse percentage calculations. For further information pertaining to this article contact: Ian Langtree at Disabled World.

Main Document

"When speaking of a 10% rise or a 10% fall, the usual interpretation is that this is relative to the initial value of that quantity."

In mathematics, a percentage is a number or ratio expressed as a fraction of 100.

Percentage is often denoted using the percent sign, "%", or the abbreviation "pct."

It comes from per cent which is short for per centum which means per hundred.

In British English, percent is sometimes written as two words (per cent, although percentage and percentile are written as one word).

The percent value is computed by multiplying the numeric value of the ratio by 100. For example, to find 50 apples as a percentage of 1250 apples, first compute the ratio 50/1250 = 0.04, and then multiply by 100 to obtain 4%. The percent value can also be found by multiplying first, so in this example the 50 would be multiplied by 100 to give 5,000, and this result would be divided by 1250 to give 4%.

To calculate a percentage of a percentage, convert both percentages to fractions of 100, or to decimals, and multiply them. For example, 50% of 40% is:

(50/100) x (40/100) = 0.50 x 0.40 = 0.20 = 20/100 = 20%.

NOTE: It is not correct to divide by 100 and use the percent sign at the same time. (E.g. 25% = 25/100 = 0.25, not 25% / 100, which actually is (25/100) / 100 = 0.0025. A term such as (100/100)% would also be incorrect, this would be read as (1) percent even if the intent was to say 100%.)


  • 1 percent (1%) = 1 part per 100 = 1/100 = 0.01 (a portion less than a whole)
  • 100 percent (100%) = 100 parts per 100 = 100/100 = 1 (a portion equal to a whole)
  • 110 percent (110%) = 110 parts per 100 = 110/100 = 1.1 (a portion greater than a whole)

When speaking of a 10% rise or a 10% fall, the usual interpretation is that this is relative to the initial value of that quantity. For example, if an item is initially priced at $200 and the price rises 10% (an increase of $20), the new price will be $220. Note that this final price is 110% of the initial price (100% + 10% = 110%).

Examples of percent changes:

  • A decrease of 100% means the final amount is zero (100% - 100% = 0%).
  • A decrease of 60% means the final amount is 40% of the original (100% - 60% = 40%).
  • An increase of 800% means the final amount is 9 times the original (100% + 800% = 900% = 9 times as large).
  • An increase of 100% in a quantity means that the final amount is 200% of the initial amount (100% of initial + 100% of increase = 200% of initial); in other words, the quantity has doubled.

In general, a change of x percent in a quantity results in a final amount that is 100+x percent of the original amount (equivalently, 1+0.01x times the original amount).

Percentage Calculator
What is % of
Or Find Percentage of...
is what percent of
Answer: %

Facts: Percentage History

The term "per cent" is derived from the Latin per centum, meaning "by the hundred".

The sign for "per cent" evolved by gradual contraction of the Italian term per cento, meaning "for a hundred".

The "per" was often abbreviated as "p." and eventually disappeared entirely.

The "cento" was contracted to two circles separated by a horizontal line, from which the modern "%" symbol is derived.


  1. Disabled World (Jul 28, 2009). Body Fat Percentage Calculator for Men and Women
  2. Disabled World (Mar 22, 2010). Height and Weight Percentile Chart Measurements
  3. Disabled World (Feb 07, 2011). Growth Percentile Calculator for Children

Comments and Discussion


     What will I receive?

Money ChartLoan Information for low income singles, families, seniors and disabled. Includes home, vehicle and personal loans.

Albert EinsteinFamous People with Disabilities - Well known people with disabilities and conditions who contributed to society.

Pink awareness ribbonList of awareness ribbon colors and their meaning. Also see our calendar of awareness dates.

Chart IconBlood Pressure Chart - What should your blood pressure be. Also see information on blood group types and compatibility.

  1. Yemen Cholera Outbreak Is The World's Worst
  2. NAELA President's Statement on the Senate Health Care Reform Legislation
  3. Non-profit Provides Assistance Dogs Free of Charge to People with Disabilities
  4. Census Bureau Facts and Statistics Show Senior U.S. Population Is Still Growing