What does UPF mean on kids' swimwear?
UPF shows how much sun protection the fabric gives. Snug fit, long sleeves and the right size make a big difference.
UPF stands for Ultraviolet Protection Factor and shows how much UV radiation a fabric lets through. It's sunscreen for textiles, similar to how SPF works for skin cream — but UPF measures both UVA and UVB that can pass through the material.
A UPF 50 garment lets through roughly 1/50 of UV radiation, about two percent. That's why UPF 50+ is common on swimwear, UV suits and sun hats for kids. For families who spend a lot of time at the beach, pool or preschool playground, UPF garments can be a simple way to give steady protection on the parts of the body that are covered.
But UPF isn't only about the number. Protection also depends on how much skin the garment covers, how tightly the fabric is woven or knit, how the garment fits, and whether it gets stretched out or wet. A too-small garment stretched over the body can give worse protection than the same fabric in the right size. Wet, thin or very light-coloured garments can also protect less than you might think.
For kids, design matters: long sleeves, a higher neckline, good fit and a sun hat can make a real difference. Remember too that UPF garments only protect the skin they cover. Face, hands, legs and other exposed areas still need shade, a hat or sunscreen.