R-value

noun

ˈär-ˌval-(ˌ)yü How to pronounce R-value (audio)
: a measure of resistance to the flow of heat through a given thickness of a material (such as insulation) with higher numbers indicating better insulating properties compare u-value

Examples of R-value in a Sentence

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Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Not only is that because sleeping-bag temperature ratings are self-reported by brands, thereby opening the category up to, well, lies, but that even with a best-case, accurately reported temperature rating, that number is calculated when paired with a 4.0 R-value pad. — Wes Siler, Outside Online, 3 June 2019 Winter campers will want an R-value of 7 and above for sleeping on top of snow and in below-freezing temperatures. — Maggie Slepian, Travel + Leisure, 11 Feb. 2025

Word History

Etymology

probably from thermal resistance

First Known Use

1948, in the meaning defined above

Time Traveler
The first known use of R-value was in 1948

Rhymes for R-value

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Browse Nearby Words

RVA
R-value
RVer
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Cite this Entry

“R-value.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/R-value. Accessed 26 Mar. 2025.

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