What does UPF 50 mean? An ultraviolet protection factor of 50 means the fabric lets through about one-fiftieth of the erythemally weighted ultraviolet radiation that falls on it, so roughly two percent reaches the skin and about 98 percent is blocked. That is the easy part. For a brand putting “UPF 50+” on a hang tag, the harder questions are which standard produced the number, under what conditions the fabric was tested, and whether the rating survives a season of salt water and washing.
This guide is written for product and sourcing leads at fishing apparel brands and distributors. It explains what a UPF rating is, which standards measure it and how they differ, what a UPF 50+ label requires, why ratings fall when fabric is wet, stretched or washed, and what to ask a manufacturer for before a claim goes on a label.
It describes standards by what they measure. It is not a substitute for the standards themselves or for legal advice on labelling in your market.
UPF vs SPF, Then the Brand’s Question
The Skin Cancer Foundation’s guide to sun protective clothing states the difference plainly: UPF measures both UVB and UVA rays, while SPF measures only UVB. SPF describes how a sunscreen behaves on skin; UPF describes how much ultraviolet radiation a fabric transmits. A consumer sees the two numbers side by side on a shelf. A brand has to produce one of them with a laboratory instrument and defend it.
So the brand’s question is not “is UPF 50 good”. It is “which test, which specimen, which conditions, and will the number still hold when the shirt is in use”.
What Is a UPF Rating, and What Does UPF 50 Mean?
A UPF rating is a ratio. AATCC’s Test Method 183 computes it from the erythemally weighted ultraviolet irradiance measured without and with a fabric specimen in the instrument. UPF 50 means the weighted irradiance with the fabric in place is one-fiftieth of the irradiance without it. The Skin Cancer Foundation puts the same thing in consumer terms: a UPF 50 fabric blocks 98 percent of the sun’s rays and allows two percent to penetrate.
What is UPF clothing, then? It is clothing made from fabric whose ultraviolet transmittance has been measured this way and that is labelled with the resulting class. Which classes exist depends on the standard:
- Under AATCC TM183 and the US labelling specification, Hohenstein’s overview of UPF standards lists UPF 15 as good, UPF 30 as very good and UPF 50 and 50+ as excellent.
- Under AS/NZS 4399:2020, ARPANSA’s guide to the Australian and New Zealand standard lists three classifications: UPF 15 is minimum protection, UPF 30 is good protection, and UPF 50 and 50+ are excellent protection.
- Under EN 13758-2 in Europe, Hohenstein lists a single threshold of UPF 40+.
In every scheme, 50+ is the top of the scale. A fabric that measures far above 50 is still labelled 50+, so two “UPF 50+” fabrics can differ considerably in measured transmittance. That matters once wet, stretched and washed conditions are considered below.
Which Standards Test UPF, and What Each Measures
Seven documents come up in fishing apparel specifications. They are not interchangeable: some are test methods, some are labelling rules, one is a specimen-preparation practice and one is a private certification scheme.
| Document | What it is | Specimen state and spectrum | Classes or threshold |
|---|---|---|---|
| AATCC TM183 (US) | Test method for ultraviolet radiation blocked or transmitted by fabrics; reports UPF and UVA/UVB blocking | Specimens may be tested dry or wet; Hohenstein notes the method uses new-condition textiles and the Albuquerque spectrum | 15 good, 30 very good, 50 and 50+ excellent |
| ASTM D6603-19 (US) | Labelling specification for textiles intended to protect against UVA and UVB; labels rest on instrumental data | Refers testing to TM183; excludes medical-device sun-protective fabrics | Uses the TM183 classes |
| ASTM D6544-25 (US) | Practice that conditions fabric by laundering, simulated sunlight and chlorinated pool water before UV testing | Intended to approximate two years of seasonal use; used with TM183 and D6603 | Not a rating; a preparation step |
| AS/NZS 4399:2020 (Australia, NZ) | Evaluation, classification and labelling standard for sun protective clothing, including body-coverage rules | Hohenstein: new, unstretched, dry fabric under the Melbourne 1 January spectrum | 15 minimum, 30 good, 50 and 50+ excellent |
| EN 13758-1 (Europe) | Test method for the erythemally weighted UV transmittance of conditioned apparel fabrics | Measured flat, unstretched or in a predefined stretched state; Hohenstein: new, dry, Albuquerque spectrum | Reported as UPF; classes applied by Part 2 |
| EN 13758-2 (Europe) | Classification and marking of UV-protective apparel | Builds on Part 1 results | UPF 40+ |
| UV Standard 801 (Hohenstein) | Private certification scheme for textiles | New, stretched, wet, abraded and washed; worst case under the Melbourne spectrum; lowest value sets the label | Levels from 10 to 80 |
Three points follow from the table. First, the common national methods rate fabric in new, dry, unstretched condition. Second, the European scheme has a single pass mark of 40+ rather than a ladder of classes. Third, only the private scheme and the US preparation practice build wet, stretched or aged conditions into the rating itself. Hohenstein’s description of UV Standard 801 states that the consumer rating is the lowest value determined in the worst-case scenario, rounded down to the next level.
What a “UPF 50+” Label Requires
The number alone is not the label. Each framework attaches conditions to it.
Australia and New Zealand. ARPANSA explains that its swing tag shows the material has been tested to AS/NZS 4399:2020 and given a UPF rating by ARPANSA’s NATA-accredited laboratory, and that the standard requires clothing to carry wording to the effect that the UPF rating applies only to the area of skin covered and that protection may be reduced if the material is wet, stretched, or affected by normal wear or chemicals. The 2020 edition also excludes low-coverage garments such as bikinis, singlets and crop tops from any sun-protection claim regardless of the fabric’s UPF, and ARPANSA notes that its test reports rate the material but do not evaluate the design or body coverage of the product.
European Union. Intertek’s bulletin on UV protective clothing (checked 2026-10-20) records that garments designed to protect skin against natural UV are treated as Category I personal protective equipment, that the fabric or garment should reach at least UPF 40, that the CE mark must appear on a permanently sewn-in label, and that the manufacturer or EU distributor should prepare and retain a technical file for ten years.
United States. ASTM’s D6603-19 is the current labelling specification for textiles intended to protect against UVA and UVB radiation. Its public scope states that the recommended labelling is based on UV-protection data collected by instrumental methods and that it supplements the existing care and fibre-content labelling rules. There is no government pre-approval; the brand holds the evidence.
For a fishing shirt sold in several markets, the practical consequence is that one test report rarely covers every label. Decide which markets matter before sampling, so the laboratory can run the right method and conditions on the production fabric.
Inherent UPF vs Finish-Based UPF
How does UPF clothing work? Fabric blocks ultraviolet radiation in two ways: by absorbing it and by reflecting it. How much it blocks is decided mostly by construction and material, and sometimes by a chemical finish added later.
Inherent UPF comes from the fabric itself. The Skin Cancer Foundation lists the drivers: densely woven or knitted cloth is more protective than sheer fabric; dark or bright colours absorb UV rays rather than letting them penetrate; unbleached cotton contains natural lignins that act as UV absorbers; and shiny polyesters and satiny silks can protect by reflecting radiation. Weight follows from density: a heavier construction of the same yarn generally transmits less. These properties are part of the fabric and do not wash out, although they can be reduced by stretch and wear.
Finish-based UPF comes from UV-absorbing agents applied during dyeing or finishing. A finish can lift a light, open fabric into a high class on a new-condition test. Whether it stays there depends on how the finish is bound to the fibre and how the garment is laundered. This is the reason specimen preparation exists: ASTM’s D6544-25 conditions fabric by laundering, simulated sunlight and chlorinated pool water precisely because, in its own words, UV resistance changes over time.
Which fabric has the highest UPF? There is no single answer by fibre name. A tightly knit, mid-weight, dark polyester commonly tests at 50+ in new condition, and so can a dense cotton twill; a light, open, pale fabric of either fibre will not. The instrument decides, which is why a brand specifies a test result rather than a fibre.
How to make UPF clothing, then, is a sequence rather than an ingredient: choose a construction and colour that reach the target inherently where possible, add a finish only if the design needs a lighter fabric than that allows, test the production fabric and colour under the standard for each market, and label with the resulting class. Our guide to choosing fabric for custom fishing shirts covers how to brief that choice.
Wet, Stretched and Washed: Where UPF Is Lost
Do UPF shirts work when wet? Partly. The Skin Cancer Foundation notes that clothing that gets stretched or wet loses some of its protective ability and becomes more transparent, and gives the example of an ordinary white T-shirt dropping from a UPF of about 7 dry to about 3 wet. A high-UPF fabric starts from a much better position, but the direction is the same, and a fishing shirt spends its working life damp.
Stretch acts in the same way. ARPANSA’s guidance on the Australian standard explains that the required label wording warns that protection may be reduced if the material is wet or stretched, and the Skin Cancer Foundation attributes the loss to fibres pulling apart and letting more UV through. Fitted sun hoodies and stretch jerseys deserve testing in a stretched state for that reason.
Does UPF wash out of clothing? Inherent UPF largely does not, although abrasion and repeated laundering can open a construction. Finish-based UPF can diminish with washing, and the rate depends on the finish. How long does UPF clothing last is therefore not a fixed number of months; it depends on whether the rating came from the fabric or a finish, how often the garment is washed, and how it is worn. The honest answer for a brand is the one the laboratory gives after conditioning.
Write the requirement into the specification, not into the marketing. A workable clause names the method and edition, the specimen, the conditions and the target class, for example: the production fabric in the production colour shall meet the stated UPF class under the named method when tested dry and wet, and again after the agreed number of launderings or after conditioning to the named preparation practice. Leave the numbers to the fabric and the laboratory; the structure of the clause is what protects the claim.
How to Test UPF Clothing and Read the Report
How to test UPF clothing is not a home procedure. The fabric is measured in a spectrophotometer by an accredited laboratory under one of the methods above; ARPANSA, for example, issues reports from a laboratory accredited by Australia’s National Association of Testing Authorities. What a brand can do is specify the test correctly and read the report critically.
| Item on the report | What to check | Why it matters |
|---|---|---|
| Method and edition | AATCC TM183, AS/NZS 4399:2020, EN 13758-1 or UV Standard 801, with the edition stated | Classes, spectra and conditions differ between them |
| Specimen identity | Fabric article, lot, weight and, above all, colour | A white and a navy of the same construction can land in different classes |
| Specimen condition | New, wet, stretched, laundered or conditioned per a preparation practice | New-dry results overstate what the shirt does on the water |
| Results reported | UPF value, UVA and UVB transmission or blocking, and the resulting class | A bare class without the measured value hides how much margin there is |
| Laboratory and date | Accredited laboratory, report number, date; whether the fabric tested is the one being bought | Reports travel between suppliers; make sure this one belongs to your fabric |
For UPF clothing manufacturers and sun protection clothing manufacturers, the questions to put in writing are: which standard the fabric was tested to, whether the tested colour is the colour being ordered, whether wet, stretched or laundered results exist, and whether a fresh test on the production lot can be arranged. Products such as our long-sleeve UPF 50+ fishing shirt and hooded sun-protection fishing shirt are the kinds of styles where that evidence should be requested for the specific fabric and colour before a label is printed.
Claims, Labels and Compliance
A UPF claim is an advertising claim. The US Federal Trade Commission’s advertising guide for small business states that advertising must be truthful and non-deceptive, that a company must have a reasonable basis for its claims before an ad runs, and that a reasonable basis means objective evidence that supports the claim. In the European Union the same garment is Category I personal protective equipment with a CE mark and a technical file, as described above. In Australia and New Zealand the label wording and the body-coverage rules come with the standard.
None of this is legal advice. It is the reason the test report, the specimen it describes and the conditions it covers should be settled before the hang tag is designed. Fabric selection decides most of the outcome; the fabric guide linked above explains how to put UPF evidence into the brief alongside weight, hand and decoration.
Frequently Asked Questions
What is UPF 50?
A fabric class, not a guarantee for the whole garment. UPF 50 fabric transmits about one-fiftieth of the erythemally weighted UV that reaches it in the test. The rating applies to the covered area, in the tested condition, for the tested colour.
Is UPF 50+ different from UPF 50?
50+ is the top class in the AS/NZS and AATCC schemes and covers every fabric that measures above 50. Ask for the measured value as well as the class to see how much margin a fabric has before wet or stretched conditions are considered.
Why does the same fabric get different ratings in different reports?
Because the methods differ in reference spectrum, specimen conditioning and rounding, and because colour, lot and finish change the result. Compare reports only when the method, condition and colour match.
Does a UPF rating cover the whole shirt?
No. ARPANSA states that its reports rate the material, not the design or coverage of the product. Mesh vents, open weaves in side panels and stretched zones are tested separately or treated as uncovered areas.
Specify UPF With CYCLODRY
Tell us the markets you sell in, the colours you plan to run and whether you need wet, stretched or post-wash results. We will say which test evidence exists for the fabrics you shortlist, which tests can be arranged on the production lot, and how the result should be written into the specification. Browse the fishing shirts and jerseys category for the styles most UPF programmes start from.
Contact CYCLODRY about UPF testing for your fishing apparel line to go through the fabric, colour and test plan together.
References
- AATCC — Test Method 183, public summary
- ASTM — D6603-19 Standard Specification for Labeling of UV-Protective Textiles
- ASTM — D6544-25 Standard Practice for Preparation of Textiles Prior to Ultraviolet (UV) Transmission Testing
- ARPANSA — Australian sun protective clothing (AS/NZS 4399:2020)
- Hohenstein — Determining UV Protection Factor (UPF) for Textiles
- Hohenstein — Certified UV Protection: UV STANDARD 801
- iTeh Standards — EN 13758-1:2001+A1:2006, public abstract
- Intertek — EU: Guidance on Requirements for UV Protective Clothing Category 1 PPE
- The Skin Cancer Foundation — Sun Protective Clothing
- FTC — Advertising FAQ’s: A Guide for Small Business
The linked pages are public summaries, laboratory overviews and regulator or foundation guidance. They describe what each standard measures and requires in general terms; they do not establish test results, ratings or certifications for CYCLODRY products, and they are not legal advice for labelling in any market.