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noun

SPF

ess-pee-EFF
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SPF (noun) means 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. Example: “The bottle was labelled SPF 30.”

noun
1
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."
"He complained that the SPF rubbed off every time he towelled down."
2
informal Informally, sunscreen itself, or any product containing it.
"Have you got any SPF in your bag?"

How to use SPF

Learner’s notes

In plain EnglishThe number on suncream that tells you how much it guards against burning.

When to use it

Written as capitals with no full stops, followed by a numeral: SPF 30. Used as a countable noun in the informal product sense.

Memory tip

Remember that the F stands for factor, not filter, and that the whole rating is about UVB and sunburn specifically.

Trace the full origin ↓
Easily confused with
UVA UVB PA rating broad-spectrum
Common pairings
SPF 50 high SPF broad-spectrum SPF SPF rating daily SPF
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Fill the gap

Can you complete this real example?

The bottle was labelled _____ 30.

Etymology

An initialism of sun protection factor.

Origin: English

Synonyms

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sun protection factor sunscreen sunblock sun cream

Related words

sunscreen sunblock

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.
What is the meaning of SPF?
"SPF" (noun) means 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.

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sunscreen sunblock