Whether you're lounging on the beach, working out in the gym or working in the office, your comfort is important. Get a comfortable fit with the Calvin Klein Underwear and Swimwear Size Guide. Our sizing guide will help you determine the correct fit based on your measurements. We also provide instructions to help you measure yourself accurately to ensure a perfect fit. After determining your measurements, we've got you covered with a wide selection of comfortable underwear and swimwear that will fit like it was made for you. Also discover our Clothing Size Guide to choose the right outfits that match your body measurements and make sure you always look and feel comfortable, despite the occasion.