SPF test is the standardized science that turns a sunscreen formula into a number you can put on a label. Hver "SPF 30" eller "SPF 50+" påstanden sidder i slutningen af en kontrolleret laboratorie- og klinisk proces - en defineret af internationale standarder, målt på ægte hud eller validerede instrumenter, and tied to the specific market where the product will be sold. For any brand developing a sunscreen, understanding that process is the difference between a claim you can defend and one that gets your product pulled from shelves.
This guide walks through how sunscreen protection is actually tested, from the lab bench to the finished label. We cover what SPF measures (and what it does not), the ISO methods behind SPF and UVA ratings, where testing fits into product development, and why requirements change depending on your target market. If you are sourcing an OEM and private label sunscreen manufacturer, these are the fundamentals that separate a capable partner from a risky one.
A quick orientation before we begin: this article focuses on markets that regulate sunscreen as a kosmetisk — the EU, Storbritannien, much of South America, Sydøstasien, Golfen, and large parts of Africa. A handful of markets treat sunscreen as a drug or therapeutic good instead, which changes both the testing regime and who is allowed to manufacture it. We will flag where that distinction matters.
jeg. What SPF Testing Actually Measures
De sun protection factor (SPF) is a measure of how well a sunscreen protects skin against UVB radiation — the part of the ultraviolet spectrum mainly responsible for sunburn. In testing terms, SPF is the ratio between the UV dose needed to redden protected skin and the dose needed to redden bare skin. An SPF of 30 means it takes roughly thirty times more UV energy to produce the same level of redness when the product is applied correctly.
Here is the single most important thing to understand, and the point most often gotten wrong: SPF says nothing about UVA protection. SPF and UVA are two separate endpoints, measured by different methods. UVA rays penetrate deeper into the skin and drive long-term damage and visible aging, while UVB drives burning. A high SPF number tells you about UVB defense only.
This is why the term broad spectrum exists. A broad-spectrum sunscreen is one proven to protect against both UVA and UVB. In cosmetic-regulated markets, the benchmark comes from the EU's recommendation on sunscreen efficacy, which advises that a sunscreen's UVA protection factor be at least one-third of its labelled SPF, together with a kritisk bølgelængde of at least 370 nm. Products meeting both conditions may carry the UVA-in-a-circle symbol. Vigtigt, "broad spectrum" confirms that UVA protection is present and proportional — it does not, on its own, tell a consumer the exact degree of that protection.
| Term | What it protects against | How it is verified |
|---|---|---|
| SPF | UVB (sunburn) | ISO 24444 (forgæves) |
| UVA -beskyttelse | UVA (deeper damage, aldring) | ISO 24442 eller ISO 24443 |
| Broad spectrum | Both UVA and UVB | UVA-PF at least 1/3 of SPF, plus critical wavelength of at least 370 nm |
II. The ISO Methods Behind the Number
Sunscreen protection is measured against a defined set of ISO standarder, each built for a specific endpoint. Because SPF (UVB) and UVA protection are distinct, they are assessed by distinct methods — and conflating them is the most common technical error in sunscreen documentation.
The reference method for SPF is ISO 24444, en forgæves test carried out on human skin. A standardized amount of product — 2 milligrams per square centimetre — is applied to the backs of a panel of volunteers, typisk 10 til 20 people spanning a range of skin tones. A solar simulator delivers controlled doses of UV light, and technicians record the minimal erythema dose (the point of clearly defined redness) on protected versus unprotected skin. The ratio between the two is the SPF.
UVA protection is measured separately. ISO 24442 is the forgæves persistent-pigment-darkening (PPD) method that underpins the PA grading system (PA+ through PA++++) used widely across Asian markets. ISO 24443 is the in vitro method that produces the UVA protection factor and critical-wavelength values the EU relies on for broad-spectrum labelling. Two newer standards add instrument-based options: ISO 23675:2024, en in vitro double-plate method for SPF, og ISO 23698:2024, a hybrid diffuse-reflectance approach that captures SPF, UVA protection factor, and critical wavelength in a single workflow without a biological response.
| ISO standard | What it measures | Method type | Noter |
|---|---|---|---|
| ISO 24444 | SPF (UVB / sunburn, MED-baseret) | In vivo | The reference method for SPF |
| ISO 24442 | UVA -beskyttelse (PPD) | In vivo | Basis of the PA grading system |
| ISO 24443 | UVA -beskyttelse (UVA-PF and critical wavelength) | In vitro | Underpins EU broad-spectrum labelling |
| ISO 23675:2024 | SPF (double-plate method) | In vitro | Published December 2024 |
| ISO 23698:2024 | SPF, UVA-PF and critical wavelength (HDRS) | Hybrid | One workflow, no biological response; published December 2024 |
The practical takeaway for brands is direct: an SPF value and a UVA rating are produced by different tests, and a complete protection claim needs both. A manufacturer that only references an SPF figure has told you half the story.
III. Where Testing Fits in Product Development
In a working sunscreen development process, testing is not a single event at the end — it runs alongside formulation from early on. The typical sequence moves from formula design, to fast in vitro screening, to confirmatory forgæves afprøvning, and finally to the supporting tests a specific claim requires.
Early in vitro methods let a formulation team iterate quickly and economically: candidate formulas can be screened for UV attenuation before committing to clinical panels. Once a formula performs well, forgæves SPF testing under ISO 24444 confirms the on-skin result. If the brand wants a vandmodstand krav, an additional test is needed — volunteers immerse in water for set intervals (almindeligt 40 minutes for "water resistant" og 80 minutes for "very water resistant") and the SPF is re-measured afterward. Each added claim lengthens the process and adds cost, which is one reason not every product carries every label.
This is where a manufacturer's testing setup directly affects a brand's timeline and budget. A partner with established in vitro screening and access to validated SPF testing can resolve formulation problems internally, rather than sending every iteration to an outside lab and waiting weeks between rounds.
Ausmetics fordel: Med mere end 28 years of cosmetics manufacturing experience and in-house SPF testing capability, Ausmetics screens and refines sunscreen formulas internally before clinical confirmation, shortening development cycles for brands targeting cosmetic-regulated markets. Production runs under ISO 22716 (GMPC) cosmetic good manufacturing practice — the relevant quality standard for sunscreen made as a cosmetic.
IV. Why Test Requirements Differ by Market
One important point before committing to any manufacturer: a sunscreen's regulatory classification is set at the national or trade-bloc level, ikke efter kontinent - så det operative spørgsmål er altid hvilket marked jeg sælger til? Over det meste af verden, solcreme er reguleret som kosmetik, typically under the EU's Regulering (Ec) 1223/2009 or frameworks modeled on it: the UK Cosmetics Regulation, ASEAN's kosmetiske direktiv på tværs af Sydøstasien, Mercosur-aligned rules in much of South America (Brazil's ANVISA, for eksempel, behandler solcreme som en registreret "Grad 2" kosmetisk), og GCC-standarder i Golfen. The notable exceptions regulate it as a drug or therapeutic good — the United States (et OTC-lægemiddel under FDA-monografien), Canada (et ikke-receptpligtigt lægemiddel eller et naturligt sundhedsprodukt), og Australien (a therapeutic good overseen by the TGA, made in pharmaceutical-grade GMP facilities). A few markets sit in hybrid categories, such as Japan's "kvasi-lægemiddel" and South Korea's "funktionel kosmetik."
These classifications shape which test methods regulators accept. EU broad-spectrum labelling, for eksempel, relies on ISO 24444 for SPF alongside the in-vitro UVA assessment under ISO 24443; Asian PA grading draws on the PPD method in ISO 24442. The standards overlap, but the required combination and the registration paperwork differ from market to market. Always confirm the rules for your specific target market before locking in a formula or a manufacturer.
V. What This Means for Choosing a Manufacturer
Forståelse SPF test gives a brand owner a sharper checklist when evaluating a sunscreen partner. The goal is to confirm that a manufacturer can not only formulate a pleasant product, but also generate the evidence your claims and your market legally require.
Questions worth asking any candidate include:
- Testing capability: Do they run in-vitro screening in-house, and which ISO methods do their SPF and UVA results follow?
- Market fit: Do they have experience producing sunscreen for your target market's regulatory framework — and is that a cosmetic market they can actually serve?
- Formulation range: Can they work across mineral, kemisk, and hybrid systems to hit your target SPF, struktur, and finish?
- Dokumentation: Will they provide the test reports and safety documentation (such as a Cosmetic Product Safety Report for the EU) you need to register and sell?
- Quality system: Do they manufacture under ISO 22716 (GMPC)?
A manufacturer that answers these clearly — with its own testing discipline and market-appropriate documentation — is one you can build a durable sunscreen line with. For brands focused on cosmetic-regulated regions, working with an experienced producent af private label solcreme that maintains in-house SPF testing removes much of the technical risk from a launch. You can also review a partner's broader testing and compliance approach through its kvalitetssikring program.
Ausmetics fordel: Ausmetics has supported more than 600 Mærker over hele verden, with an R&D team led by Dr. Jadir Nunes, tidligere global præsident for IFSCC. For sunscreen, that means formulation across mineral, kemisk, and hybrid systems, internal SPF screening, and documentation aligned with cosmetic-market requirements — all under one ISO 22716-certified roof.
Ofte stillede spørgsmål
How is SPF measured?
SPF is measured with an forgæves test defined by ISO 24444. A set amount of sunscreen (2 mg/cm²) is applied to the backs of a panel of human volunteers, who are then exposed to controlled doses of UV light from a solar simulator. Technicians record the minimal erythema dose — the point at which clearly defined redness appears — on both protected and unprotected skin. The SPF is the ratio between those two doses. Newer in-vitro and hybrid methods, ISO 23675 og ISO 23698, can also generate SPF values using instruments rather than human panels.
What is the difference between SPF and UVA protection?
They cover two different parts of the ultraviolet spectrum. SPF measures protection against UVB rays, which cause sunburn, while UVA protection addresses the deeper-penetrating rays linked to long-term damage and visible aging. The two are measured by separate methods — ISO 24444 for SPF, og ISO 24442 eller ISO 24443 for UVA. A sunscreen labelled broad spectrum has been shown to protect against both, which is why dermatology bodies recommend broad-spectrum products rather than relying on the SPF number alone.
What does a "broad spectrum" claim require?
In cosmetic-regulated markets that follow the EU model, a broad-spectrum claim requires evidence of meaningful UVA protection alongside the SPF. The EU recommends that the UVA protection factor be at least one-third of the labelled SPF, and that the product reach a critical wavelength of at least 370 nm. This is verified through separate UVA testing, most often the in-vitro method in ISO 24443. Because requirements vary, brands should confirm the exact threshold and labelling rules for each market they enter.
Can sunscreen SPF be tested without human subjects?
Increasingly, ja. Traditional SPF testing under ISO 24444 uses human volunteers, but two standards published in December 2024 offer alternatives: ISO 23675 is an in-vitro double-plate method for SPF, og ISO 23698 is a hybrid approach that measures SPF, UVA protection factor, and critical wavelength together without a biological reaction. These methods support faster formulation screening and reduce reliance on clinical panels, though the in-vivo reference method remains important for final claims in many markets.
How does SPF testing affect a product's development timeline?
Testing is one of the larger variables in a sunscreen launch schedule. In-vitro screening is relatively quick and lets a formulation team refine a product early, but confirmatory in-vivo SPF testing and any water-resistance testing add weeks and cost. Each additional claim — higher SPF, broad spectrum, water resistance — requires its own evidence. Working with a manufacturer that runs internal SPF screening can compress this timeline, because formulation issues are caught and corrected before a formula reaches the clinical stage.
Konklusion og næste trin
The number on a sunscreen label is the visible end of an invisible process. SPF test follows defined ISO methods, SPF and UVA are measured separately, and the exact combination of tests a product needs depends on the market it is sold into. For a brand, fluency in these fundamentals makes for better product decisions and a much clearer conversation with any potential manufacturer.
If you are planning a sunscreen line for cosmetic-regulated markets, the next step is partnering with a manufacturer that pairs strong formulation with disciplined testing. Explore how Ausmetics supports brands as an OEM and private label sunscreen manufacturer, eller kontakt vores team at diskutere din formel, target SPF, and market requirements.