Finding underwear that fits just right can change your whole day—from the moment you get dressed to when you finally unwind. At The Underwear Store, most bottoms come in sizes Small to XL, with some styles available in 2XL. But how do you know what size really fits you best? It all starts with knowing exactly how to measure your waist and hips, and matching your measurements to the right size on our S–XL size chart.

This guide walks you through easy, foolproof measuring tips, style-specific fit advice, troubleshooting common fit issues, and answers all your burning questions about underwear sizing. Whether you’re shopping for briefs, trunks, or thongs, this post will help you find your perfect fit for ultimate comfort and confidence all day long.