ALPHX Men’s Underwear Size Guide
Use our detailed men’s underwear size chart to find the perfect fit for your body type. Whether you prefer briefs, trunks, boxer briefs, or union pants, ALPHX styles are designed to match your waist size with precision comfort.
Note: Our men’s briefs are engineered without a leg inseam for minimal coverage and maximum support, offering a streamlined, supportive fit you can count on every day.
| Size | Waist (in) | Waist (cm) | Trunk Inseam | Boxer Brief Inseam | Brief | Union Pant Inseam |
|---|---|---|---|---|---|---|
| XS | 25–27 | 64–69 | 1.5 | 3.0 | — | 29.0 |
| S | 28–30 | 71–76 | 1.5 | 3.8 | — | 29.8 |
| M | 31–33 | 79–84 | 1.8 | 4.5 | — | 30.5 |
| L | 34–37 | 86–91 | 2.8 | 5.5 | — | 31.3 |
| XL | 38–41 | 94–102 | 3.8 | 6.5 | — | 32.0 |
| XXL | 42–45 | 104–114 | 4.8 | 7.5 | — | 32.8 |
Measure Yourself for the Best Fit
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Waist Measurement
Measure Your Waist
Wrap a flexible tape measure where your underwear naturally sits—typically right at the hip bone. This is your waist measurement.
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Thigh Measurement
Measure Your Thighs
For Boxer Briefs and Union Pants, measure about 4.5" down from the crotch. For Trunks and Briefs, use 2" down. This helps us suggest the ideal fit based on your thigh shape.
Answer 4 Quick Questions to Find Your ALPHX Fit
Find Your Fit Quiz
Answer a few quick questions to find the perfect ALPHX fit, size, and style.
Calculating your fit...
Fit Quiz FAQs
Fit Quiz FAQ – ALPHX Sizing, Styles & Returns Explained
Have questions about your ALPHX fit? This FAQ covers everything you need to know about our men’s underwear sizing quiz—from how we recommend the right size and fit for your body type, to what styles are included. Learn how our stretch fabric adapts, what to do if you’re between sizes, and how our easy return and exchange policy ensures you get the perfect fit.
What sizes does ALPHX offer?
We offer sizes from XS(25–27") to XXL (42–44") and fits tailored to both slim/average and large/muscular thighs.
How do I know if I need the Athletic or Modern Fit?
If you have muscular or fuller thighs, go with Athletic Fit. If you’re slim through the legs, Modern Fit is ideal.
What if I’m in between sizes?
If you're between sizes or at the upper end of a size range, size up for a more relaxed fit or down for a snug, supportive feel. Our fabric is designed to stretch and adapt to your body.
Will my fit recommendation include product suggestions?
Yes. You’ll select your preferred style as part of the quiz, but the recommended size and fit will apply across Boxer Briefs, Trunks, and Union Pants. Since Briefs don’t cover your thighs, we only offer them in Modern Fit. If you're interested in Briefs, we suggest taking the quiz again with that style selected to get the most accurate size recommendation.
Q: Can I return or exchange if they don’t fit?
Absolutely. We make returns and exchanges as hassle-free as possible. If your ALPHX underwear doesn’t fit quite right, you can start a return or exchange through our easy process. Click here to view our Returns, Exchanges, and Be Assured Guarantee policies.