Sun Protection Hat Guide: UPF, Mesh and Brim Size

UPF stands for ultraviolet protection factor. It measures how much UVA and UVB radiation gets through a fabric to your skin (Skin Cancer Foundation). A UPF 50 fabric lets through about one-fiftieth of the UV that falls on it, so it blocks about 98% (Cancer Council Australia).

The rating is measured on unstretched, dry material (Cancer Council Australia). Fabric protects less when it is wet or stretched, so a hat that is soaked or pulled tight will not perform at its label.

In Australia and New Zealand, the standard is AS/NZS 4399:2020. It sorts fabric into three classes (ARPANSA):

UV blocked is from Cancer Council Australia.

SPF is for sunscreen, and UPF is for fabric. SPF measures how much UV it takes to redden skin with sunscreen on compared with bare skin (Skin Cancer Foundation). UPF measures how much UVA and UVB passes through a fabric.

The two work together. A hat protects the skin it shades. Sunscreen covers the skin it does not reach, such as the lower face, chin, neck and shoulders. A higher number on either one does not replace the other.

Only partly. The solid parts of a mesh hat can block UV, but open mesh lets sunlight straight through to your scalp. A lab rating does not show this. In the US, the AATCC 183 test often used for hats measures only the main material. It does not look at the hat's design, including mesh or eyelets (Journal study, PMC).

The UK and Australian standards are stricter about openings. They allow no more than 10 ventilation eyelets, each smaller than 3 mm and at least 10 mm apart (Journal study, PMC). MD Anderson Cancer Center gives a simple home test: if you can hold a hat up to a bright light and see light shining through, it will not give enough sun protection (MD Anderson).

How we handle mesh

We do not give a sun protection rating to any hat with open mesh or open vents, even when its wide brim is cut from 50+ material. Mesh covered by a solid outer layer, and small mesh eyelets, do not stop a hat from being rated.

A mesh hat can still be a good choice for heat and airflow. Just treat the crown as unprotected: add sunscreen to your scalp or part line, or choose a closed-crown hat for long days outside.

These hats are made from good materials. We leave the rating off because of their design, not because of a gap in testing.

They protect the top of your head and your forehead, but they leave most of your face, ears and neck exposed. ARPANSA says caps give reasonable protection to the scalp, forehead and nose, but almost none to the neck and ears (ARPANSA). Its measurements put a baseball cap's protection factor at about 9 on the forehead and 4 on the nose, but barely above 1 on the cheeks, ears, chin and neck.

Under the Australian standard, caps and visors cannot claim or display a UPF rating, because they do not cover enough of the head (SunSmart). A trucker hat is a cap with a mesh back, so it has both problems: a short peak and an open crown.

We do not give a sun protection rating to any cap. If you wear one, use sunscreen on your ears, neck and cheeks.

A higher protection factor means better protection. A protection factor of 2 means it takes about twice as long to burn. Figures are from ARPANSA. They measure the shade a brim casts, which is different from a fabric's UPF.

Brim width matters more than any number on a tag. Dermatologists most often find basal and squamous cell skin cancers on the head and neck, including the face, scalp and ears (MD Anderson). A short brim leaves those areas in the sun. Health groups set these minimums:

Sources: Cancer Council Australia, SunSmart, Skin Cancer Foundation, journal study summarizing US health societies and MD Anderson. Conversions to inches are rounded.

Our own floor is 2.5 inches. We do not rate any hat with a shorter brim, because a sun rating on a short-brimmed hat could lead someone to stay out longer than is safe. For long days on the water or the trail, we suggest 3 inches or more.

It depends on the weave. ARPANSA notes that straw hats can have spaces between the fibers, and suggests looking for a straw hat with a fabric lining (ARPANSA). MD Anderson points out that straw hats often have large gaps in the weave (MD Anderson).

A tightly woven raffia or straw with a wide brim can earn a strong rating. A loose or open weave cannot. Our straw and raffia hats do not all carry the same rating, so check the rating on each product page.

Most sun protection claims in the hat industry describe a fabric, not a hat. We think that gap matters, so here is exactly how we handle it.

Step 1: we test the material

We test all our hat materials with ARPANSA, the Australian Radiation Protection and Nuclear Safety Agency. It measures the UPF of each fabric itself: how much UV passes through a felt, a cotton, a woven raffia or a straw. ARPANSA's reports rate the material only; they do not judge a product's design or coverage (ARPANSA). That is why we add two rules of our own.

Rule 1: no rating for open mesh or open vents

A lab measures a flat piece of fabric. A hat with open mesh or a vented crown has openings that let UV through. The fabric's number is still true, but it does not describe the protection on your scalp. So we do not rate these hats, even when the brim is cut from 50+ material. Mesh under a solid outer layer, and small mesh eyelets, are fine.

Rule 2: no rating for brims under 2.5 inches

A short brim leaves the ears, the back of the neck and much of the face uncovered, however good the fabric is. We do not rate those hats.

What a rating on our site means

If a hat on our site has a sun protection rating, its material was tested, its brim is at least 2.5 inches, and it has no open mesh or open vents. If a hat has no rating, that is usually a deliberate choice, not a gap in testing. Ask us and we will tell you which it is: customerservice@connerhats.com.

Most of the hats we rate are UPF 50+. Three, the Tuscany, Latin Quarter and Brays Beach sun hats, are rated UPF 25+, and their product pages say so.

The World Health Organization recommends sun protection whenever the UV index is 3 or higher. Water, sand and fresh snow reflect UV and raise your exposure (WHO). A brim shades you from above. It cannot block UV reflected up from below.

ARPANSA says a hat will rarely give enough protection on its own when the UV index is 3 or higher (ARPANSA). Pair your hat with sunscreen, sunglasses, clothing that covers your skin and shade. Cancer Council Australia says a broad-brimmed hat can cut UV to the eyes by more than 50%, and a broad-brimmed hat with sunglasses that meet the Australian standard can cut it by up to 98% (Cancer Council Australia).

Every hat below has a tested material, no open mesh or open vents, and a brim of at least 2.5 inches. Each product page gives its own rating.