Essential items, clothes, weather considerations, and what you don't need — packing smart for a Bangkok trip.
Light, breathable clothes (cotton, linen); modest outfit for temples; flip-flops/sandals; a light rain jacket or umbrella (May–Oct); one nice outfit if dining at upscale restaurants.
High-SPF sunscreen (local brands are cheaper but US/EU brands more familiar), hat or cap, sunglasses, insect repellent (dengue/mosquitoes in rainy season).
Charger (Thailand uses 220V, 50Hz — bring adapter or buy cheap locally), phone, power bank if doing day trips.
Passport (check expiration — need 6+ months), travel insurance details, copies of important docs, some USD or EUR (easier to exchange than most currencies).
Toiletries (cheap and available everywhere), medications (pharmacies sell most OTC without prescription), expensive skin care (tourist shops are pricey, but CVS-equivalent shops are normal price).