Strategies SPF Laboratory Test Results: What Do SPF 30, SPF 50, and SPF 50+ Mean?
Sunscreen plays an important role in protecting the skin from ultraviolet (UV) radiation. When consumers choose sunscreen products, one of the most noticeable pieces of information on the packaging is the Sun Protection Factor (SPF), commonly displayed as SPF 30, SPF 50, or SPF 50+.
But where do these numbers come from? SPF values are not simply determined by calculating the amount of UV filters included in a formulation. They are supported by testing performed according to appropriate methodologies.
Therefore, SPF laboratory test results provide important data for evaluating sunscreen performance and supporting product claims. SPF is a relative measure of the UV exposure required to produce erythema or sunburn on sunscreen-protected skin compared with unprotected skin.
This means that SPF should not simply be interpreted as the exact number of hours a person can safely spend in the sun. So, what do SPF 30, SPF 50, and SPF 50+ actually mean from a laboratory testing perspective?
Table of Content:
- What Is SPF?
- How Is an SPF Value Determined?
- What Does SPF 30 Mean?
- What Does SPF 50 Mean?
- What Does SPF 50+ Mean?
- Does Higher SPF Mean Complete UV Protection?
- Why Can SPF Laboratory Test Results Differ from Formulation Expectations?
- Why Is SPF Testing Important for Sunscreen Manufacturers?
- SPF Laboratory Test Results Are More Than a Label Number
What Is SPF?
SPF stands for Sun Protection Factor. It represents a sunscreen product's relative level of protection against UV-induced erythema, which is primarily associated with UVB radiation.
Conceptually, SPF compares the UV dose required to produce erythema on sunscreen-protected skin with the dose required to produce the same response on unprotected skin. However, SPF is not simply a measurement of time.
UV intensity varies depending on time of day, geographic location, weather conditions, season, and environmental factors. Real-world protection is also influenced by how much sunscreen is applied, how evenly it is distributed, sweating, swimming, rubbing, and reapplication.
Therefore, SPF laboratory test results should be interpreted according to the conditions and methodology under which the product was evaluated.
Read Also:
Sunscreen Labeled SPF 50: Does the Value Match the Test Results?
How Is an SPF Value Determined?
Sunscreen performance can be evaluated using different approaches depending on the purpose and applicable methodology.
In Vitro Testing
In vitro methods evaluate sunscreen performance without directly measuring erythema responses on human skin. These methods may use UV spectrophotometric measurements to evaluate how a sunscreen formulation interacts with ultraviolet radiation.
Such testing can be useful during product development and preliminary formulation screening. However, in vitro and in vivo testing do not necessarily produce identical SPF values.
Therefore, the testing method and intended use of the resulting data should always be considered when interpreting SPF laboratory test results.
In Vivo Testing
In vivo SPF testing evaluates sunscreen protection by assessing the response of human skin to controlled UV exposure. ISO 24444:2019 specifies an international method for the in vivo determination of the Sun Protection Factor of sunscreen products.
The standard provides a basis for evaluating sunscreen protection against erythema induced by solar ultraviolet radiation. For manufacturers, this means that the testing methodology is an essential part of interpreting the SPF value obtained from the laboratory.
What Does SPF 30 Mean?
SPF 30 indicates a higher level of sunburn protection than lower SPF values when evaluated according to the applicable SPF test methodology. However, SPF 30 should not be interpreted as meaning that a consumer can automatically stay in the sun exactly 30 times longer.
Real-world UV exposure is much more complex. The actual level of protection can be affected by application thickness, uniformity, sweating, water exposure, physical activity, and reapplication.
Therefore, SPF 30 is better understood as a relative measure of sunscreen performance under defined testing conditions. For manufacturers, SPF laboratory test results provide the data needed to determine whether the developed formulation achieves the intended level of protection.
What Does SPF 50 Mean?
SPF 50 represents a higher level of sunburn protection than SPF 30 according to SPF testing parameters. However, an increase in the SPF number does not represent a directly proportional increase in protection.
For example, SPF 50 should not simply be interpreted as providing twice the protection of SPF 25. The SPF value is derived from the relationship between UV exposure and erythema response under standardized testing conditions.
Therefore, SPF laboratory test results are more appropriately viewed as performance measurements rather than simply marketing numbers displayed on sunscreen packaging.
What Does SPF 50+ Mean?
SPF 50 and SPF 50+ may look almost identical to consumers, but the “+” has a specific labeling context. In Indonesia, BPOM regulations categorize SPF values of 50 or above as providing a very high level of protection.
When the determined SPF value is greater than 50, the product labeling may state SPF 50+. Therefore, the plus sign should not simply be interpreted as a marketing expression meaning “extra strong”.
It relates to the SPF value obtained through testing and the applicable labeling framework. This is another reason why manufacturers need reliable SPF laboratory test results before determining the SPF claim displayed on a sunscreen product.
Does Higher SPF Mean Complete UV Protection?
Not necessarily. SPF primarily describes protection against erythema or sunburn, which is strongly associated with UVB radiation.
However, sunlight also contains UVA radiation. UVA can penetrate the skin and contribute to biological effects such as photoaging.
Therefore, sunscreen evaluation should not necessarily stop at the SPF number. UVA or broad-spectrum protection may also need to be evaluated according to relevant methods and regulatory requirements.
Consequently, a sunscreen labeled SPF 50 should not automatically be assumed to provide optimal UVA protection based solely on its SPF number. SPF and broad-spectrum protection should be understood as related but distinct aspects of sunscreen performance.
Why Can SPF Laboratory Test Results Differ from Formulation Expectations?
A sunscreen may be designed to achieve a specific SPF based on the types and concentrations of UV filters used. However, theoretical formulation calculations do not necessarily predict the final measured SPF value.
Sunscreen performance can be influenced by:
- type and concentration of UV filters;
- UV filter combinations;
- formulation homogeneity;
- emulsion characteristics;
- viscosity;
- film formation;
- distribution of filters on the skin;
- formulation stability; and
- interactions between ingredients.
Two sunscreen products may contain similar UV filters but still perform differently because their formulation characteristics are not identical. Therefore, the presence and concentration of UV filters alone cannot fully determine the final SPF value.
SPF laboratory test results provide experimental data on how the finished formulation performs under defined testing conditions.
Why Is SPF Testing Important for Sunscreen Manufacturers?
SPF testing is not simply about obtaining a number for product packaging. For manufacturers, testing data can support several stages of sunscreen development.
It can help determine whether a formulation achieves its target performance, allow R&D teams to compare different prototypes, support product claims, and reduce reliance on theoretical assumptions based solely on UV filter composition. This becomes particularly important because consumers frequently use SPF values when comparing sunscreen products.
Product claims should therefore be supported by relevant and appropriate testing data.
SPF Laboratory Test Results Are More Than a Label Number
A simple SPF number can represent a substantial amount of product development and laboratory evaluation. For consumers, SPF provides a way to compare relative levels of sunscreen protection.
For manufacturers, however, SPF laboratory test results can support formulation evaluation, R&D decisions, product claims, and quality-related assessments. Testing should therefore be considered during product development rather than only after packaging and marketing materials have been finalized.
Support Your SPF Claims with Laboratory Testing Data
Don't rely solely on formulation calculations or UV filter claims. Support your sunscreen performance claims with measurable SPF testing data!
IML Testing & Research provides Efficacy Testing services to help companies obtain data on sunscreen performance and support the evaluation of UV protection claims according to their testing requirements.
Developing a sunscreen targeting SPF 30, SPF 50, or SPF 50+? Contact IML Testing & Research today and discuss your SPF testing requirements with our team!
Author & Editor: Lina
References
International Organization for Standardization. (2019). ISO 24444:2019 — Cosmetics — Sun protection test methods — In vivo determination of the sun protection factor (SPF).
International Organization for Standardization. (2022). ISO 24444:2019/Amd 1:2022 — Cosmetics — Sun protection test methods — In vivo determination of the sun protection factor (SPF) — Amendment 1.
Badan Pengawas Obat dan Makanan Republik Indonesia. (2023). Penjelasan BPOM RI tentang Informasi Kosmetik Tabir Surya (Sunscreen) dengan Klaim SPF.
Badan Pengawas Obat dan Makanan Republik Indonesia. (2024). Peraturan BPOM Nomor 18 Tahun 2024 tentang Penandaan, Promosi, dan Iklan Kosmetik.
U.S. Food and Drug Administration. Sun Protection Factor (SPF). Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. Labeling and Effectiveness Testing: Sunscreen Drug Products for Over-the-Counter Human Use — Small Entity Compliance Guide.
