Cansado vs. agotado
While both cansado and agotado can translate to tired in English, they represent different levels of fatigue and have distinct uses. Cansado is the general term for being tired, whereas agotado implies a much more intense state of exhaustion or being completely used up.
Cansado
A1This is the most common and general word for tired. It describes a normal state of physical or mental weariness from effort or lack of rest. It is less intense than agotado.
Después de un largo día de trabajo, me siento muy cansado.
(After a long day of work, I feel very tired.)
Estoy cansado de escuchar siempre las mismas quejas.
(I am tired of always hearing the same complaints.)
Los niños jugaron toda la tarde y ahora están un poco cansados.
(The children played all afternoon and now they are a little tired.)
Solo leí dos capítulos, pero mi mente ya está cansada.
(I only read two chapters, but my mind is already tired.)
Agotado
B1This word means exhausted, drained, or worn out. It describes an extreme state of tiredness where one's energy has been completely depleted. It is also used for inanimate objects to mean sold out or used up.
Tras correr la maratón, el atleta estaba completamente agotado.
(After running the marathon, the athlete was completely exhausted.)
Después de semanas de intenso estudio, se sentía mentalmente agotado.
(After weeks of intense studying, he felt mentally exhausted.)
Quise comprar el libro, pero la edición estaba agotada en todas las librerías.
(I wanted to buy the book, but the edition was sold out in all the bookstores.)
Los recursos naturales de la región están casi agotados.
(The natural resources of the region are almost depleted.)
Summary
In essence, use cansado for everyday tiredness, whether physical or mental. Use agotado to express a profound state of exhaustion, as if all your energy is gone. Remember that agotado is also the correct choice when you mean that a product is sold out or a resource is depleted.