How to Find the Right Underwear Size Without Trying It On

Quick answer

Measure your natural waist at the point where your waistband normally sits, then measure your hips at the fullest point. Match those two numbers to the brand's size chart, and if you fall between sizes, size up for boxer briefs because the fabric needs room to stretch and recover. Always check the return policy before ordering, especially on surplus or final-sale items.

Buying underwear online saves time, but it only works if you know your measurements. Most men guess their size from old pairs, and that guess is often one size off. The fix is simple: take two measurements with a soft tape, compare them to the brand's chart, and use a few fit rules to decide between sizes.

This process works for any style, including boxer briefs, trunks, and briefs. It also helps you avoid the most common mistake, which is ordering based on your pants size instead of your body measurements. Pants sizes vary by cut and brand, so they are a poor proxy for underwear.

Measure your waist at the right spot

Stand relaxed and wrap a soft measuring tape around your waist where you want the waistband to sit. For most men, that is at or just below the navel, not at the narrowest point of the torso. Keep the tape level and snug but not tight. Breathe normally and record the number in inches or centimeters.

A common mistake is measuring over thick clothing or pulling the tape tight enough to compress the skin. Both distort the number. If you get a reading that falls between two whole inches, round to the nearest half inch and write it down. You will use this number together with your hip measurement to pick a size.

• Checkpoint: The tape should touch your skin but not leave a mark.
• If you are unsure, measure twice and average the two numbers.

Measure your hips at the fullest point

Your hip measurement matters because boxer briefs and trunks have to pass over your hips and seat. Stand with your feet together and wrap the tape around the widest part of your hips and buttocks. Keep the tape parallel to the floor. This is usually a few inches below your waist measurement, and it is often larger.

If your hip measurement is more than two inches larger than your waist, use the hip number as your primary guide when the size chart lists both. A waist-only fit can feel fine when you stand still but pull or bind when you sit, squat, or move. That is a common reason guys return underwear that seemed correct on paper.

• Checkpoint: The tape should stay level all the way around, not ride up in back.
• Write down both numbers before you open the size chart.

Read the size chart like a fit range, not a rule

Most size charts give a waist range, such as 32 to 34 inches, rather than a single number. Treat that range as a zone. If your waist is at the bottom of a range and your hips are at the top, you are between sizes. For boxer briefs, size up so the fabric can stretch with you instead of fighting you.

Also look at what the chart does not say. If a chart lists only waist and not hip, and you have thicker thighs or a larger seat, use your hip measurement to choose the larger size when you are close to a boundary. The goal is a waistband that stays put without pinching and legs that do not ride up.

• Checkpoint: If you are between sizes and the fabric has four-way stretch, sizing up is usually the safer call.
• Do not assume your pants size equals your underwear size.

Match the fit to the leg length and pouch style

Size is only half the fit. Leg length and pouch design change how a pair feels. A 6-inch inseam boxer brief sits mid-thigh and suits average to thicker legs and sports. A 9-inch inseam is better if your legs rub or chafe, and some guys use it as a replacement for running tights. A 3-inch inseam is for average to thinner legs and a shorter feel.

Pouch design matters too. AnatoMax offers maximum anatomical separation, while AnatoFree gives anatomical freedom with a smaller pouch. Neither is better in the abstract; they simply suit different preferences. If you already know which pouch style you like, keep that constant and change only the size when you order a new pair.

• Checkpoint: If you are unsure about pouch style, start with the one you already wear.
• Leg length and pouch are separate decisions from size.

Use the return policy as your safety net

Before you order, read the return and exchange rules. Some items, including surplus or final-sale garments, may not be returnable. That changes your risk calculation. If returns are allowed, ordering two sizes and sending one back is a practical way to dial in your fit. If returns are not allowed, be more conservative and size up rather than down.

A good habit is to order one pair in your best-guess size first, wear it for a full day, and note where it pinches, rides, or bunches. Then use that feedback for your next order. This is faster than guessing repeatedly and cheaper than keeping pairs that never feel right.

• Checkpoint: Check the return window and any final-sale exclusions before checkout.
• One test pair beats a bulk order when you are unsure of your size.

Your step-by-step sizing routine

1. Gather a soft measuring tape and a mirror: Use a flexible tape, not a metal ruler or a piece of string you guess at later. Stand in front of a mirror so you can see whether the tape stays level around your body. Checkpoint: If you do not have a soft tape, use a strip of paper and mark it, then measure the marks with a ruler.
2. Measure your natural waist: Wrap the tape where your waistband normally sits, usually at or just below the navel. Keep it snug but not tight, and breathe normally. Checkpoint: The tape should not leave a red mark or slide down when you relax.
3. Measure your hips at the fullest point: Stand with feet together and run the tape around the widest part of your hips and seat. Keep the tape parallel to the floor. Checkpoint: If your hip number is more than two inches larger than your waist, use the hip number as your main guide.
4. Compare both numbers to the brand size chart: Find the size range that contains your waist and hip measurements. If you land in two different sizes, choose the larger one for boxer briefs. Checkpoint: A size chart range is a zone, not a single target number.
5. Decide between sizes based on fabric and fit: Four-way stretch fabrics forgive a slightly snug fit, but a waistband that pinches or legs that ride up mean you should size up. If you are between sizes and the fabric has limited stretch, size up. Checkpoint: Never size down hoping for a tighter fit; that is the fastest route to returns.
6. Check the return policy before you buy: Confirm whether the item can be returned or exchanged. Surplus and final-sale items often cannot, so be more certain of your size before ordering those. Checkpoint: If returns are allowed, order two sizes and return the one that fits worse.
7. Test one pair for a full day: Wear your first pair through a normal day, including sitting, walking, and any activity. Note any pinching, riding up, or bunching. Checkpoint: Use those notes for your next order instead of starting from scratch.

How real options differ in fit

• FreeMan - Boxer Brief 6 inch Leg: Boxer Brief mid length legs 6” inseam, ideal for average to thicker legs and sports, with an AnatoFree Pouch and a durable Bamboo Rayon/Lycra blend. The 6-inch leg and four-way stretch suit everyday wear and activity, while the AnatoFree pouch gives a smaller, less separated fit than AnatoMax.
• EveryMan - Boxer Brief 9 inch Leg: Boxer Brief with long legs 9” inseam, ideal for those whose legs rub and chafe, with an AnatoMax Pouch and a soft, stay-put logo waistband. The longer leg reduces friction between thighs, and the AnatoMax pouch provides maximum anatomical separation for guys who prefer that feel.
• EcoSurplus - EveryMan - Boxer Brief 6 inch Leg: 1st grade surplus fabric and waistband with production quality identical to regular production; note that there are no refunds or exchanges on EcoSurplus garments. The lower catalog price is attractive, but the no-return policy means you should be confident in your size before ordering this option.

Finding your underwear size without trying it on comes down to two honest measurements and a smart reading of the size chart. Measure your waist and hips, size up when you are between sizes, and check the return policy before you commit. Do that once, and every future order gets easier.