SPF
0 antonyms and opposites of SPF, grouped by meaning.
Noun — A number printed on sunscreen that indicates how much protection the product gives against UVB, the band of ultraviolet light chiefly responsible for sunburn. It is measured by comparing how long treated skin takes to redden with how long untreated skin takes.
Synonyms by Meaning
1. noun
A number printed on sunscreen that indicates how much protection the product gives against UVB, the band of ultraviolet light chiefly responsible for sunburn. It is measured by comparing how long treated skin takes to redden with how long untreated skin takes.
“The bottle was labelled SPF 30.”
How to use SPF
The word patterns that sound natural to a native speaker.
Written as capitals with no full stops, followed by a numeral: SPF 30. Used as a countable noun in the informal product sense.
Etymology
An initialism of sun protection factor.
Full origin of SPF →Frequently asked questions
Does SPF cover UVA as well as UVB?
No. The SPF number relates to UVB only. Protection against UVA is indicated separately, by markings such as a star rating or the word broad-spectrum, depending on the country.
Is SPF 50 twice as protective as SPF 25?
In terms of ultraviolet let through, yes: SPF is a ratio, so SPF 25 admits about 1/25 of UVB and SPF 50 about 1/50 — half as much. What changes little is the share BLOCKED, which goes from roughly 96% to roughly 98%, so the gap sounds smaller when expressed that way. Both figures describe the same measurement, and both assume the product is applied thickly and often enough to match lab conditions.
What is the difference between sunscreen and sunblock?
In everyday speech they are used interchangeably. Historically sunblock suggested an opaque product sitting on the skin's surface, while sunscreen suggested a filter, but regulators in several countries now discourage the word sunblock as misleading.