When a garment label states or implies that the garment is sun protective, the manufacturer, retailer, or certifier is making a claim.  The claim is for SUNBURN PROTECTION.  In the US, it is the Federal Trade Commissions’ task to monitor such claims.  In Australia, the Radiation Protection Laboratory monitors such claims.  Whether any monitoring is undertaken in the United States is unknown.  Whether any action has been taken or has needed to be against those making false claims is also not known.


Items of information on labels that are most helpful during decision making are:

            a certifier’s name and/or the name of the labeling document on which the protection claim is made,

            a protection category designation,

            a UPF or SFP value,

            the percent of UVA radiation blocked by the fabric.



A wise practice before purchasing a garment labeled as being sun protective is to look for the name of the document on which the claim is made.  Two are:

                        AS/NZS 4399

                        ASTM 6603- 00.


The first is the Australian/New Zealand’s document prepared by their joint standard setting organization.  The second is the document prepared by a UV Protective Textiles Committee within ASTM International, a major US standard setting organization.  You can find summaries of these documents on this website and learn how claims made using them are alike and different.



One type of certifier uses the labeling documents of national standard setting organizations.  Manufacturers of UV protective garments send garments to the certifier who tests the garments according to an external organization’s directions.  The external organization is usually a national standard setting organization such as ASTM or Standards Australia/New Zealand.  Two examples of such labeling are:


Australian Radiation Protection Laboratory





AMC Cancer Research Center*







* No longer certifies UV protective fabrics/garments.


Another type of certifier prepares “in-house” criteria on which a UV protection claim is made and place a seal of approval on the product.  The criteria may not be available to the public (to you).  Two examples are:



The Skin Cancer Foundation Seal

International Test Association for Applied UV Protection Seal








The words “Good,” “Very Good,” and “Excellent” on labels which also say ASTM 6603-00 or AS/NZS 4399designate relative amount of protection provided by the fabric from which the garment is made.  As the protection category designators imply, a garment labeled as Excellent will allow any individual to remain longer in the sun before his/her skin reddens (sunburns) than if that individual was wearing a garment in the Very Good or Good protection category.


Protection category designators (good, very good, and excellent) do NOT designate how much skin surface is covered by the garment.  Consumers can easily judge skin coverage and are encouraged to purchase a) garments designed to cover the skin – at least more than the usual amount and b) garments made from fabrics with the appropriate fabric protection category designation.


Which Protection Category Designation (Good, Very Good, or Excellent) is necessary depends on

a)      the wearer’s sensitivity to the sun (how quickly their uncovered skin sunburns when exposed to solar ultraviolet radiation),

b)      the length of time the wearer will be in the sun, and

c)      the intensity of the UV radiation during that time period.


Table I relates these ideas.  Note that persons with dark skin and hair (and do not have UV sensitivity to UV due to medications they have taken or medical therapies they have had) can select garments rated good, very good, and excellent but need to be careful of the conditions in which they wear those garments.  At the other extreme, individuals with UV sensitivities should always select garments with the Excellent UV protection designation and also be careful of how long they are in the sun (exposure time) and the time of day they are in the sun (usually avoiding exposure between 10:00 and 3:00 when UV intensity is at its highest).


TABLE 1: Relationship of Protection Category to Wearer’s UV sensitivity and Wearing Conditions.






Dark skin and hair

Fair skin, blond or red hair

Ultraviolet light sensitive1


Garment to be worn for 8 hours or more including the time when ultraviolet exposure is at maximum intensity.


Garment to be worn all day at high altitude location

Under most conditions of use sunburn would not occur.

OK, but avoid being outside between 10:00 and 3:00 when ultraviolet exposure is at a maximum as sunburn may occur. 50+ UPF value necessary.

Very Good

OK, if Garment to be worn outside 4 hours or less during the most UV intense times of the day (10:00 to 3:00).

OK, if garment to be worn for short periods of time, especially in early morning and late afternoon

Do not select.


OK, if garment to be worn for short periods of time, especially in early morning and late afternoon

Ok, of garment to be worn for short periods of time, especially in early morning and late afternoon

Do not select.


1has an inherited (genetic) ultraviolet sensitivity (such as persons with xeroderma pigmentosum or on increased ultraviolet sensitivity due to medications taken or exposure to medical therapies known to enhance skin UV sensitivity.



Labels SHOULD show a UPF value or an SPF value.  UPF stands for Ultraviolet Protection Factor and SPF stands for Sun Protection Factor.  The number that follows UPF or SPF indicates “how much longer a person can stay in the sun before their skin begins to redden in comparison to the time for that person’s uncovered skin to redden under identical exposure conditions.”  The higher the number following UPF/SPF, the longer a person whose skin is covered with the fabric can stay out of doors in the day time before their skin will redden.


So, if you were to stand outside with one arm bare (uncovered with fabric) and one arm covered with a fabric with a 30 UPF/SPF value and noticed that your bare arm skin started to redden in 10 minutes, then you should expect your fabric covered arm to start to redden in 300 minutes (10 X 30) which would be in 5 hours provided the intensity of the UV remains the same as during the 10 minutes of initial exposure.  Assuming the exposure conditions remain the same, at 5 hours your fabric covered skin will have received the same dose of UV – been damaged to the same extent -- as those skin area you exposed for just 10 minutes.


Another way of interpreting UPF/SPF values is in terms of reduction of the dose of UV radiation your skin under the fabric receives.  Wearing a well-designed garment (meaning one that covers your skin) made with fabric with a UPF value of 15 will reduce solar UV exposure to the skin beneath the garment by a factor of 15.  That fabric will allow one fifteenth of the UV radiation that strikes its surface to pass through it.


The benefit of wearing UV protective clothing is that skin damage to fabric covered skin is slowed.  Again, the claim is for sunburn protection!!!!  Other skin benefits may be a reduction in premature skin aging and decreased potential for the development of skin cancer lesions (basal cell, melanoma, etc…), but these benefits are not claimed because the testing to determine UPF/SPF does not consider reduction in skin wrinkling, age spots, etc. which are based on reduction in UVA exposure.


Relationship of UPF Value to Protection Category

The connection of UPF/SPF values with Protection Category designation are provided in Table 2.

TABLE 2:  Relationship of UPF value to Protection Category Designation


Protection Category Designation

UPF/SPF Values (a) Associated with Designation

% UV blocked by fabric



93.3 – 95.9

Very Good


96.0 – 97.4


40 to 50+

97.5 or more


(a)    UPF is used when the scientist/laboratory technician collects UV transmittance data using a laboratory instrument called a spectrophotometer and then uses that data to calculate the UPF value.  SPF is used when the scientist/laboratory technician asks a human subject to come to the laboratory so that UV radiation of various does strengths can be directed to his/her upper back or arm skin, some of which is covered and some not covered, and then uses this data to calculate the SPF.  UPF and SPF values for the same fabric are not identical but the difference for any fabric can be accounted for.


Label UPF Values

You might think that you will find garments labeled as having UPF values of 17, 23, etc. but you should be suspicious if that is the case.  Manufacturers who are using the recognized labeling standards (ASTM 6609-00 and AS/NZS 4399 will provide UPF values in increments of 5 starting at 15, and ending at 50 so values are 15, 20, 25, 30, 35, 40, and 50.  They will use 50+ to indicate protection higher than 50.


50 UPF and 50+ UPF

The amount of protection for fabric covered skin is considered to be significantly different between each 5 unit increase in UPF value.  So selecting a garment with the higher UPF value is wise.  However, be aware that garments with the 50+ rating may not offer substantially more protection than those with a UPF 50 value.  Don’t pay a premium price to get the 50+.


Relationship of UPF values to Standard Labeling Document

Should you be deciding between two garments each made with fabric of identical UPF values but one label indicates that UPF was arrived at following AS/NZS 4399 and the other label says ASTM 6603-00, you might want to select the ASTM 6603-00 garment.  The reason is that at the time the UPF value was determined for ASTM 6603-00 garment the fabric had been laundered 50 times and subjected to ultraviolet radiation.  In contrast the UPF value for the AS/NZS garment was “as is” or “new condition” at time of testing.  You know then that selecting the ASTM 6603-00 garment means the UPF value on the label is the lowest UPF value to be expected over the life of the garment.



Labels that state % UVA radiation blocked by the fabric help in purchase decision making.  The higher the % UVA blocked the greater the slowing of pre-mature skin aging that can be caused by sun exposure.  While UVB rays are primarily responsible for burning the skin, it is UVA rays that cause pre-mature skin ageing.