Do I still need to wear SPF with UPF clothing?

UPF clothing will protect the skin that it is covering, but that usually does not cover the hands and neck. Make sure any exposed areas are covered in sunscreen before heading out into the sun, and it doesn't hurt to wear sunscreen underneath your UPF clothing either. The more protection you have against the sun's radiation, the less you can expect to end up with sun damaged skin at the end of a long day.

Which fabrics protect you most from the sun?

As a general rule, fabrics that are dark in color, have a tight weave, and feel thick make for the best sun protection out of everyday materials. Polyester is also a great choice as it reflects the sun's harmful UVA and UVB rays away from the body. However, for maximum protection it's best to opt for clothing that has a UPF rating of 50+, as this blocks out over 98% of the sun's harmful radiation.