UPF vs SPF: what the rating on sun protective clothing actually means

SPF: a guide for sunscreen, on skin

SPF stands for Sun Protection Factor. Cancer Council describes it as a guide to how well a sunscreen protects your skin from sunburn.

Two things about SPF surprise people.

First, sunburn is mainly caused by UVB. UVA reaches deeper into the skin, and Cancer Council says both UVA and UVB add to skin damage, early ageing and skin cancer risk. That is what "broad-spectrum" on the bottle is for. A broad-spectrum sunscreen filters both UVA and UVB. It is a separate claim from the SPF number, so look for both.

Second, the SPF you get depends on how you use it. Sunscreen works best when it is used exactly as the label says. Cancer Council's advice is to use about one teaspoon for each arm, and around seven teaspoons for an adult's whole body. Put it on 20 minutes before going outside. Then reapply every two hours, and straight away after swimming, sweating or towelling off.

That is a lot to remember halfway through a round, or with dirt on your hands in the garden. Add sweat and a towel, and it is easy to end up with less protection than the bottle suggests.

UPF: a measure of what gets through fabric

UPF stands for Ultraviolet Protection Factor. In one line: UPF tells you how much of the sun's UV gets through a fabric.

Rather than measuring sunburn on skin, a UPF test shines UV through samples of fabric in a laboratory and measures how much passes through. It looks at both UVA and UVB. The result is a number. Divide one by it and you get the fraction of UV that gets through.

The current Australian standard sorts fabric into these groups, according to Cancer Council and ARPANSA:

• UPF 15: Minimum protection, blocking about 93.3% of UV.
• UPF 30: Good protection, blocking about 96.7% of UV.
• UPF 50 and 50+: Excellent protection, blocking 98% or more.

UPF 50+ is the top of the scale. It means the fabric lets through no more than one fiftieth of the UV hitting it, so it blocks at least 98%. Cancer Council recommends UPF 50 and 50+. There is more on the numbers in UPF 30 vs 40 vs 50+ and what UPF 50+ means.

The difference that actually matters

Here is the practical difference, and it is the main reason people cover up.

Sunscreen needs topping up. Fabric does not.

Sunscreen can rub off on your shirt, sweat off and wash off, and the advice is to reapply every two hours. In practice, that is hard to keep up mid-round or mid-job. Golfers know this problem well. See why golfers burn even with sunscreen on.

A UPF 50+ sleeve in good condition goes on once and stays on. It cannot be put on too thinly, and you cannot miss a patch. As long as it fits well and stays in place, the cover at 4pm is the same as it was at 9am. The one thing to watch is moisture. Cancer Council says fabric protects less when wet, so on a long, sweaty day, a dry spare pair is a good idea.

None of this makes sunscreen bad. Cancer Council says regular sunscreen use helps, and calls sunscreen the last line of defence, used together with clothing, hats, shade and sunglasses. Sunscreen is what you use on the skin you cannot cover.

Does washing or stretching ruin UPF?

It depends on the fabric and how it gets its rating.

Cancer Council explains that some clothing is treated with UV absorbers to boost its protection. If yours is, check the label and follow the care instructions. Other fabrics get their protection mainly from how tightly they are knitted or woven, their thickness and their colour.

A few things can lower the protection of any fabric:

• Stretching. ARPANSA says stretching a knitted fabric usually lowers its UPF, because the gaps between the threads open up. That is why a well-fitting garment matters.
• Wetness. Fabrics give less protection when wet. A sweat-soaked shirt in the garden is doing less than you might think.
• Wear and fading. Old, threadbare or faded clothes may protect less over time.

Ordinary clothes still give some protection. Cancer Council notes fabric does not need a UPF label to help. But without a test, you do not know how much. For IceRays sleeves, follow the care label that comes with them, and replace them when the fabric looks thin or worn. Our care guide has more.

How to read a UPF claim without being fooled

A number is only as good as the testing behind it. Anyone can print "UPF 50+" on a label.

So ask three questions. Who tested it? When? And what exactly was tested? In Australia, ARPANSA, the Australian Radiation Protection and Nuclear Safety Agency, is a government agency, and it offers a fabric testing service.

For the record, IceRays sleeves were tested by ARPANSA in 2015 (black sample). The report, reference 10484-1B, rated a Black Aqua-x/Spandex sleeve sample UPF 50+, in the Excellent category. It rates the material, not the sleeve design, and it covers that black sample rather than every colour sold today. It is a test result, not an endorsement of IceRays. You can read the full details on our test report page (PDF, opens in a new tab).

So which should you use?

Both, on different parts of you.

Cover what you can with tested fabric. It needs nothing more from you once it is on. Use sunscreen on what is left: your face, ears, neck and the backs of your hands. And wear a broad-brimmed hat, because your scalp and the tops of your ears get a lot of sun that no arm sleeve will help with. Check the UV index, and when it is 3 or above, follow all five SunSmart steps.

The point is not that sunscreen is bad. It is that sunscreen depends on you applying it well and often, while fabric just needs putting on.

If you want that on your arms, IceRays UPF 50+ sleeves slip on in seconds. One size fits all adults. A 4-pack is AUD 120, which is $30 a pair and saves $31.80 compared with four single pairs. In the US it is USD 100.

Related guides

• Do arm sleeves protect from sun? The short answer, and how to spot an untested sleeve.
• Arm sleeves vs sunscreen: a fair side-by-side.
• Sun protection for golfers: why your arms burn even with sunscreen on.
• Gardening in the sun: how to cover up and stay comfortable.
• How to care for sun protective arm sleeves.
• The complete guide to UV arm sleeves.

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