The Thai name for the thin rice noodles used in Pad Thai is sen lek.
In Thai, เส้นเล็ก means “small” or “thin strands.” Sen lek are narrow, flat rice noodles that become pliable when soaked or briefly softened before stir-frying. Their moderate width helps them absorb Pad Thai’s tamarind-based sauce while remaining chewy rather than turning into a smooth paste.
Pad Thai is often described broadly as a rice-noodle dish, but Thai noodle terminology distinguishes several shapes. Sen yai means wide noodles, while sen mi refers to very thin rice vermicelli. Soba is a Japanese buckwheat noodle and is not the traditional noodle used for Pad Thai. Vermicelli can appear in other Thai dishes, but it is narrower than the classic Pad Thai noodle.
Noodle choice can vary outside Thailand, especially in restaurant and home recipes. Still, sen lek is the conventional Thai term associated with the medium-thin, flat rice noodles used for Pad Thai. The dish’s name is also connected to Chinese-influenced rice-noodle cooking traditions that became part of Thai street-food culture.