How do you respond to kumustas in spanish?

To respond to "¿Cómo estás?" in Spanish, you can say "Estoy bien, gracias," which means "I am good, thank you." Other options include "Estoy mal" (I'm not well) if you're feeling down, or "Más o menos" (so-so) if you're feeling average. You can also ask back, "¿Y tú?" to show interest in the other person's well-being.