UPF standards vary. There is an American and an Australian version. I think both only test new, unworn, unwashed, unstretched fabric, so the rating can be misleading for normal use. There is a newer UV standard 801 from a private group that supposedly tests the fabric after several wash cycles and (I think but not sure) some amount of stretch, but I think very few companies actually advertise this test. I might think about buying those next time though. I've always worn long sleeve shirts and pants with UPF 50 from REI, and also summer long finger gloves. It's really itchy when you sunburn your fingers. I wear sunscreen on face and neck.