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.
ALPHX Boxer Briefs Size Chart
Modern & AthleticUse thigh measurement to decide between Modern or Athletic. If near max, size up.
| Size | Waist (in) | Modern Thigh | Modern Max | Athletic Thigh | Athletic Max |
|---|---|---|---|---|---|
| XS | 25–27 | 12.5–18.5 | 19.0 | — | — |
| S | 28–30 | 13.5–20.0 | 20.5 | 14.5–21.5 | 22.0 |
| M | 31–33 | 14.5–21.5 | 22.0 | 15.5–23.0 | 23.5 |
| L | 34–37 | 15.5–23.0 | 23.5 | 16.5–24.5 | 25.0 |
| XL | 38–41 | 16.5–24.5 | 25.0 | 17.5–26.0 | 26.5 |
| XXL | 42–45 | 17.5–26.0 | 26.5 | — | — |
ALPHX Trunks Size Chart
Modern & AthleticThigh drives fit selection. If you're close to max, choose next size or Athletic fit.
| Size | Waist (in) | Modern Thigh | Modern Max | Athletic Thigh | Athletic Max |
|---|---|---|---|---|---|
| XS | 25–27 | 15.5–23.0 | 23.5 | — | — |
| S | 28–30 | 16.5–24.5 | 25.0 | 17.5–26.0 | 26.5 |
| M | 31–33 | 17.5–26.0 | 26.5 | 18.5–27.5 | 28.0 |
| L | 34–37 | 18.5–27.5 | 28.0 | 19.5–29.0 | 29.5 |
| XL | 38–41 | 19.5–29.0 | 29.5 | 20.5–30.5 | 31.0 |
| XXL | 42–45 | 20.5–30.5 | 31.0 | — | — |
ALPHX Briefs Size Chart
Modern OnlyBriefs follow Modern fit only.
| Size | Waist (in) | Modern Thigh | Modern Max |
|---|---|---|---|
| XS | 25–27 | 17.0–25.5 | 25.5 |
| S | 28–30 | 18.5–27.5 | 28.0 |
| M | 31–33 | 20.0–30.0 | 30.0 |
| L | 34–37 | 21.5–32.0 | 32.5 |
| XL | 38–41 | 23.0–34.5 | 34.5 |
| XXL | 42–45 | 24.5–36.5 | 37.0 |
Measure Yourself for the Best Fit
Wrap a flexible tape measure around your body as indicated by letters A for waist and B for thigh — using the diagram below that matches your style, since the exact measuring point changes from style to style.
Once you’ve measured your waist and thigh, or use our quick Fit Quiz below to find your perfect ALPHX size and fit for your preferred style.
Precision Fit
Your result won't just be a size — it'll tell you exactly how it fits through the thigh. Relaxed, Optimal, and Secure are all comfortable fits; we just tell you what to expect before you buy.
Relaxed · Optimal · Secure
-
Relaxed:
Extra room, a looser feel through the thigh.
-
Optimal:
The sweet spot — full support without feeling tight.
-
Secure:
A snugger, closer fit with more hold and support.
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 — how we recommend the right size and fit for your body type, what Relaxed, Optimal, and Secure mean, what to do if you're between sizes, and how our easy return and exchange policy has you covered either way.
What do Relaxed, Optimal, and Secure mean?
These terms describe how a size will actually feel through the thigh, based on your measurements— not just whether it technically fits.
Relaxed means extra room and a looser feel. Optimal is the sweet spot: fully supported without feeling tight. Secure means a snugger, closer fit with more hold and support. We tell you which one you're getting instead of leaving you to find out after you've already ordered.
Why did the quiz recommend a different size than my usual?
Waist size alone doesn't tell the whole story — thigh measurement matters just as much for how underwear actually fits. If your usual waist size would run tight through the thigh, the quiz automatically checks the next size up and recommends it instead, so you get a better fit through the leg without guessing. We never size you down from your true waist — only up, and only when it actually helps.
What if nothing fits me well?
If your measurements fall outside what Modern or Athletic Fit currently covers, the quiz will tell you honestly instead of forcing a bad recommendation. Reach out to us and we'll help you find the best option we have today.
What if I don't fit Modern or Athletic yet?
We know two fits don't cover every build yet — particularly larger, more muscular thighs — and we're developing additional fits to close that gap. That's the whole point of Precision Fit: we'd rather tell you honestly than force a size that won't work. Take the Fit Quiz to see exactly where you land.
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.