Underwear Size Chart Explained: How to Measure Yourself

Quick answer

Measure your natural waist with a soft tape, then compare that number to the brand's own underwear size chart. Choose the size that matches your measurement, not the size you wear in jeans. When you're between sizes, size up for comfort. A quick check of the product page's size options—like the Colour and Size choices on Cocksox briefs—confirms what's available before you order.

If you've ever bought underwear that felt too tight or rode up, the problem usually isn't the brand—it's the sizing. Men's underwear sizing varies between labels, and a size chart is only useful if you know which body measurement to compare against it.

This guide walks you through measuring your waist at home, reading an underwear size chart correctly, and using that number to find your underwear size. It takes about two minutes and saves you from guessing.

Why your jeans size isn't your underwear size

Jeans and trousers are cut with room to move, and their waistbands sit at different heights depending on the style. Underwear, by contrast, sits directly against the body and relies on a snug, consistent fit to stay in place. That's why a 32-inch jean waist doesn't automatically mean a 32-inch underwear waist.

Brands also design their size charts around their own patterns. A brief from one label may run smaller than a boxer brief from another. The reliable approach is to measure your body, then match that number to the specific chart on the product page you're buying from.

• Never assume your trouser size equals your underwear size.
• Always check the chart for the exact style and brand you're buying.

What you need to measure yourself accurately

You only need a flexible measuring tape and a mirror, or a friend if you want a second set of eyes. A cloth tape used for sewing works best because it bends with your body. If you don't have one, a piece of string and a ruler will do—just mark the string and measure it flat.

Wear lightweight clothing or measure against bare skin. Bulky fabrics add phantom inches and throw off the result. Stand relaxed with your feet together and breathe normally; don't suck in or pull the tape tight.

• Use a soft tape, not a stiff metal one.
• Measure over bare skin or thin underwear, not thick clothing.

How to find your natural waist

Your natural waist is the narrowest point of your torso, usually just above the belly button and below the ribcage. It's not the same as where your jeans sit. To find it, bend slightly to one side—the crease that forms is your natural waistline.

Wrap the tape around that point, keeping it level all the way around. It should sit flat against your skin without digging in. Note the number in inches or centimetres, whichever matches the size chart you'll use.

• Keep the tape parallel to the floor—a tilted tape gives a false reading.
• Write the number down immediately so you don't rely on memory.

Reading a men's underwear size chart

Most charts list sizes like S, M, L, XL alongside a waist range, for example 30–32 inches. Find the range that includes your measurement. If your waist falls exactly on a boundary, the larger size is usually the safer pick for all-day comfort.

Some charts also reference hip measurement, especially for bikini briefs and high-cut styles where coverage matters. If a chart includes both waist and hip, use waist as your primary number and hip as a tiebreaker when you're between sizes.

• Match your measurement to the range, not to the letter you 'usually' wear.
• If waist and hip point to different sizes, prioritise the waist for briefs and boxer briefs.

When to size up or size down

Size up if you're between sizes, if you prefer a looser feel, or if the fabric has limited stretch. Size down only if the chart shows you're at the very bottom of a range and you want a compression-like fit—and even then, be cautious with styles that have a defined pouch.

Fabric matters here. Two-way stretch materials, like the Italian-made ribbed fabric used in some sports briefs, move with you and forgive a slightly imperfect measurement. Firmer fabrics with less give leave less room for error.

• Between sizes? Go up for comfort, especially for everyday wear.
• Limited-stretch fabrics leave less margin—measure carefully.

How to check the fit once it arrives

Put the underwear on and check three things: the waistband should sit flat without rolling, the leg openings shouldn't pinch or gap, and nothing should require constant adjusting. If you're tugging at it within five minutes, the size is wrong.

A good fit feels supportive but not restrictive. If the pouch or front panel pulls the fabric tight across the hips, you likely need the next size up. If the waistband slides down when you walk, the size is too large.

• Waistband flat, legs comfortable, no constant adjusting.
• Still unsure? Most stores accept returns on unworn underwear—check the policy first.

Your 5-step measuring routine

1. 1. Find your natural waist: Bend to one side and note the crease—that's your natural waist, not your jeans waistline. Checkpoint: the tape should sit above your belly button and below your ribs.
2. 2. Measure with a soft tape: Wrap the tape level around your natural waist, flat against the skin, and breathe normally. Mistake to avoid: pulling the tape tight or letting it tilt.
3. 3. Write the number down: Record your waist measurement in inches or centimetres, matching the unit on the size chart. Checkpoint: measure twice to confirm the same number.
4. 4. Match it to the brand's chart: Find the size range that includes your measurement on the specific product page you're buying from. Mistake to avoid: defaulting to the size you wear in other brands.
5. 5. Decide on borderline sizes: If you're between sizes, choose the larger one for everyday comfort, or the smaller only for a compression fit in high-stretch fabric. Next step: check the product's available Colour and Size options before ordering.

How sizing plays out in real styles

• CX76BR Flexmode Sports Brief: Made from a premium Italian-made ribbed fabric with two-way stretch and exceptional breathability, in the CX76 cut with a Contour Pouch. Two-way stretch means the fabric moves with you, so a slightly snug measurement is less likely to feel restrictive during training.
• CX01 Supplex Brief: Made from Supplex fabric that holds shape, supports, and wicks moisture away, with a unique enhancing pouch. A shape-holding fabric keeps its fit over time, so getting your measurement right at purchase matters more than relying on the fabric to loosen up.
• CX94 Supplex Boxer Brief: Combines a boxer cut with the Original Pouch for an enhancing lift, in signature Supplex fabric for all-day freshness. Boxer briefs cover more of the thigh, so if your hip measurement is near the top of a range, sizing up prevents the legs from feeling tight.

Getting your underwear size right comes down to one accurate waist measurement and the discipline to match it to the brand's own chart rather than your jeans label. Measure once, write it down, and keep it handy—future orders become a two-minute job instead of a gamble.