Updated 2026
Pack enough cotton underwear to last a week and you'll have flexibility with laundry. Don't pack excessive underwear; you'll wash frequently. One week's supply is sufficient.
Why cotton: It breathes, wicks moisture, and dries relatively quickly. Synthetic blends work too. Avoid all-synthetic if you're in tropical climates—heat and sweat require breathable fabric.
How much to pack:
- 7-8 pairs of cotton underwear (allowing daily wear with one laundry day missed)
- 1-2 pairs of synthetic quick-dry underwear (for situations where drying is difficult)
Why not more: Underwear weighs almost nothing per piece, but it accumulates. Twelve pairs means you're carrying stuff you'll rarely use. Seven pairs forces regular laundry, which you should be doing anyway.
Washing considerations: Hand-wash underwear in your hostel/hotel sink. Drying takes 4-8 hours in tropical humidity. Synthetic quick-dry versions are ready in 2-3 hours. For this reason, having one pair of quick-dry is valuable on days when laundry is urgent.
The math: Washing underwear every 3-4 days is standard. Seven pairs means you can go longer if needed without running out. That's flexibility. More pairs create pack weight and filler.
Don't overthink this. Pack basic cotton underwear, wash regularly, and you're fine.