Underwear, Thermals & Socks
Alpha scales, waist guides and foot-length sock sizing
Underwear uses a simple 1–5 / S–XXL letter scale that maps to waist ranges; thermals hug the body with negative ease; socks follow foot-length shoe scales.
Men's Underwear — EU / UK-US
EU underwear runs 1–5; UK/US runs S–XXL. The number 1–5 maps to the letter, not to a waist. For the waist range behind each letter, use the letter guide below and the continental chest/waist block on the Tops page.
EU 1–5 is a code that maps to S–XXL. Read the waist behind it, not the number itself.
Underwear code conversion
Waist Guide Behind the Letter
Translate the alpha bucket into actual waist numbers — the only reliable anchor. Underwear is the most vanity-scaled garment.
The letter on the pack is often smaller than the body the pack will fit. Use waist cm (or EU 1–5) as the anchor.
Alpha to waist
Thermal Base Layers (Long Johns / Thermals)
Follow the men's chest scale (S–XXL) but with negative ease — they stretch to hug the body. A size M thermal targets roughly 100 cm chest / 86 cm waist, whereas a normal-fit M T-shirt targets the same chest with more ease.
Socks
Sized by foot length in the regional scales — buy socks on the same scale as your shoes. Some brands add S/M/L (≈ EU 36–40 / 40–44 / 44+).
Use the same scale as your shoes. See Shoes for Mondopoint/EU/UK/US equivalence.
Sock sizing by foot length
Common Mistakes
Fit & common mistakes
- Reading underwear EU 1–5 as waist-inches — it is a code, not a measure.
- Buying socks by shoe-size letter when sock scales are often simpler (S/M/L) — always check EU/cm.
- Trusting pack letters for stretch garments — stretch buys fit; size down or pick the comfort you want.
Need help?
Try our Find my size tool for a personalized recommendation, or visit How to measure to learn how to take accurate measurements.