ra·​tio | \ ˈrā-(ˌ)shō How to pronounce ratio (audio) , -shē-ˌō \
plural ratios

Definition of ratio

1a : the indicated quotient of two mathematical expressions
b : the relationship in quantity, amount, or size between two or more things : proportion
2 : the expression of the relative values of gold and silver as determined by a country's currency laws

Keep scrolling for more

Synonyms for ratio


Visit the Thesaurus for More 

Examples of ratio in a Sentence

What is the length-to-width ratio? the ratio of students to teachers in the school is nine to one
Recent Examples on the Web In Wisconsin, that ratio is over three to one on television and radio ads, with Biden having spent more than $27 million so far, compared to the president's $7.5 million. Sarah Ewall-wice, CBS News, "Biden heavily outspends Trump in closing weeks of campaign," 21 Oct. 2020 At the end of the financial crisis in 2009, the ratio was close to 10% before slowly narrowing through 2015. Vince Golle, Bloomberg.com, "U.S. Budget Gap Tripled to Record $3.1 Trillion in Fiscal 2020," 16 Oct. 2020 The ratio of the two different lengths of its sides is y. Quanta Magazine, "Celebrating the Playful Magic of John Horton Conway," 15 Oct. 2020 That ratio is the norm in the health care and caregiving industries, not the exception. Mattie Kahn, Glamour, "The Guardians of Elmhurst," 13 Oct. 2020 Simply mix the cement powder with a little water; check the label directions, but the ratio is usually three parts cement to one part water. Joseph Truini, Popular Mechanics, "How to Waterproof Your Basement," 12 Oct. 2020 In the past 10 years, the ratio has been as high as five grouse per active hunter. Tony Kennedy, Star Tribune, "Small game survey shows greater hunting success for pheasants, grouse," 8 Oct. 2020 For investors, however, that ratio may still be too high in today’s world. Telis Demos, WSJ, "Banks Can Only Tighten Their Belts So Much," 2 Oct. 2020 In the New York district, one nurse has been responsible for contact tracing for about 8,200 employees; in Detroit, the ratio is two nurses per 11,600 workers; and in Atlanta, one for 12,500. Maryam Jameel, ProPublica, "Poorly Protected Postal Workers Are Catching COVID-19 by the Thousands. It’s One More Threat to Voting by Mail.," 18 Sep. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ratio.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of ratio

1660, in the meaning defined at sense 1a

History and Etymology for ratio

Latin, computation, reason — more at reason entry 1

Keep scrolling for more

Learn More about ratio

Time Traveler for ratio

Time Traveler

The first known use of ratio was in 1660

See more words from the same year

Statistics for ratio

Last Updated

25 Oct 2020

Cite this Entry

“Ratio.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ratio. Accessed 30 Oct. 2020.

Keep scrolling for more

More Definitions for ratio


How to pronounce ratio (audio)

English Language Learners Definition of ratio

: the relationship that exists between the size, number, or amount of two things and that is often represented by two numbers


ra·​tio | \ ˈrā-shō How to pronounce ratio (audio) , -shē-ˌō \
plural ratios

Kids Definition of ratio

: the relationship in number or quantity between two or more things the ratio of teachers to students


ra·​tio | \ ˈrā-(ˌ)shō, -shē-ˌō How to pronounce ratio (audio) \
plural ratios

Medical Definition of ratio

: the relationship in quantity, amount, or size between two or more things — see sex ratio

Keep scrolling for more

Comments on ratio

What made you want to look up ratio? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Here Be Dragons: A Creature Identification Quiz

  • monster werewolf photo
  • Which is a synonym of werewolf?
Spell It

Can you spell these 10 commonly misspelled words?

Syn City

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!