Quick answer

Measure your natural waist—the crease above your hip bones—with a soft tape, keeping it snug but not tight. That number is your starting point on any men's underwear size chart, but the final call comes down to the brand's size range and the fabric's stretch. For Pair of Thieves, the SuperFit line runs from S to XL, and the fabric blend tells you how much give you'll get.

Why your pants size isn't your underwear size

Your jeans might say 32, but that number reflects where the brand wants the waistband to sit, not your body's actual measurement. Underwear sits directly against skin, so it needs to follow your true waist, not a denim vanity size. A tape measure gives you a consistent number you can compare across brands. If you're between sizes, the fabric content is your tiebreaker: a blend with more spandex will stretch further and recover better, while a higher polyamide or nylon content feels cooler but has less give.

What the size chart actually measures

Most men's underwear size charts list waist ranges in inches—for example, S (28–30), M (31–33), L (34–36), XL (37–39). These ranges assume you're measuring your natural waist, not your hips or the top of your jeans. If your measurement lands exactly on a boundary, size up for boxer briefs: a slightly looser waistband won't roll or dig, and the legs will stay put without riding up. The one exception is if you prefer a very compressive fit for sports—then stay at your measured size.

How to measure at home without a tailor's tape

No soft tape? Use a piece of string or a charging cable, wrap it around your natural waist, mark where it overlaps, then lay it flat against a ruler. Stand relaxed and breathe normally—don't suck in. Measure twice to catch any slip. Write the number down; you'll want it when you compare against a brand's chart or reorder.

Step-by-step: measure and choose your boxer brief size

  1. Find your natural waist: Stand in front of a mirror and locate the crease where your torso bends side to side—that's your natural waist, usually just above your belly button. Don't measure over clothing or at the top of your jeans. Common mistake: measuring at the hip bone or where your pants sit. That gives you a number that's too low and leads to a waistband that digs.
  2. Wrap the tape and check the tension: Pass a soft measuring tape around your natural waist. It should sit flush against your skin without compressing it. Breathe out normally and read the number where the tape meets. Checkpoint: you should be able to slide one finger under the tape. If it leaves a red mark, it's too tight.
  3. Compare to the brand's size chart: Match your measurement to the range on the chart. For Pair of Thieves, if you measure 32 inches, you're likely a Medium. If you're exactly between two sizes, look at the fabric blend—higher spandex (like the 20% in the Pouch style) gives more stretch and can make the smaller size viable. Common mistake: assuming all brands size the same. Always check the specific chart.
  4. Decide based on fit preference and style: If you want a relaxed feel, size up. If you prefer a compressive, athletic fit, stay at your measured size—especially in styles with more spandex. Also consider inseam: a 5-inch inseam (like the SuperFit Mesh Boxer Briefs) sits higher on the thigh, while a longer inseam (like the Long Boxer Briefs) provides more coverage. Checkpoint: order a 2-pack first to test the fit before committing to a larger pack.
  5. Wash and reassess: Wash according to the care label—machine wash warm, gentle cycle, tumble dry low. Pre-shrunk fabrics (like the Pouch Boxer Briefs) won't change size, but non-pre-shrunk blends may shrink slightly. If they feel tight after the first wash, that's your signal to size up next time. Next step: note the brand and size that worked, so you can reorder with confidence.

How Pair of Thieves SuperFit styles match up