UPF Sun Protection Explained
In brief: UPF, or Ultraviolet Protection Factor, is a rating of how effectively a fabric blocks the sun's ultraviolet radiation from reaching your skin. A UPF 50 garment lets through only a small fraction of UV, blocking the large majority. Unlike sunscreen's SPF, UPF measures both UVA and UVB protection and does not wear off. Tighter weaves, darker colours and certain fibres and finishes raise a fabric's UPF, making sun-protective clothing a useful layer for outdoor activity.
What is UPF?
UPF stands for Ultraviolet Protection Factor, a standardised rating of how much of the sun's ultraviolet radiation a fabric blocks from reaching the skin underneath. The number tells you the level of protection: a UPF 50 fabric, for example, allows only a small fraction of UV through and blocks the large majority of it, while lower numbers block less. UPF is the clothing equivalent of the SPF rating on sunscreen, but applied to fabric. It gives a clear, measurable way to compare how sun-protective different garments are, which matters because not all clothing shields the skin as well as people assume.
UPF vs SPF
UPF and SPF both relate to sun protection but are not the same. SPF, used on sunscreen, primarily measures protection against UVB, the rays mainly responsible for sunburn, and it relies on being applied correctly and reapplied as it wears off. UPF, used on fabric, measures protection against both UVB and UVA radiation, and it does not rub off or need reapplying, working consistently as long as you wear the garment. This makes sun-protective clothing a reliable, low-effort layer of defence: once you have it on, it keeps protecting, complementing sunscreen on the skin that remains exposed.
What makes fabric sun-protective
Several factors determine a fabric's UPF. Weave or knit density is one of the most important: a tight, closely constructed fabric leaves fewer gaps for UV to pass through than a loose, open one. Colour matters too, as darker and more vivid colours tend to absorb more UV than pale shades. Fibre type plays a role, with some synthetics and treated fabrics blocking UV better than others, and special UV-absorbing finishes can be added to boost protection. Thickness and how much the fabric stretches also count, because stretching a fabric thin opens up its structure and can lower its effective protection.
When sun-protective clothing helps
UPF-rated clothing is genuinely useful for anyone spending extended time outdoors, whether hiking, running, on the water or simply in strong sun. It covers large areas of skin reliably without the need to reapply anything, which is especially valuable on the move or when sweating, where sunscreen can wash off. It does not replace sunscreen entirely, since exposed areas like the face, neck and hands still need protecting, but it dramatically reduces the area you have to worry about. For sustained outdoor activity in bright conditions, a high-UPF layer is an easy and effective addition.
Sun-protective clothing at OD's Designer Clothing
At OD's Designer Clothing we stock outdoor and performance clothing from premium brands, including pieces designed with sun protection in mind for active days in bright conditions. UPF-rated layers pair naturally with breathable, moisture-wicking fabrics for warm-weather activity. We offer next-day delivery and free click and collect, and customers in the North West are welcome to view the ranges in person at our St Helens store.