Todo vs. cada
While both todo and cada can sometimes be translated as every in English, they are not interchangeable. The key difference lies in whether you are referring to a group as a whole or to the individual members within that group.
Todo
A1The word todo (and its forms toda, todos, todas) means all or the whole. It refers to the entirety of something or a group of things collectively. It must agree in gender and number with the noun it modifies. When used with a singular noun to mean the whole, it is typically followed by a definite article like el or la.
Comí todo el pastel yo solo.
(I ate the whole cake by myself.)
Limpió toda la casa en una tarde.
(He cleaned the entire house in one afternoon.)
Todos los estudiantes aprobaron el examen.
(All the students passed the exam.)
Hablé con todas mis amigas ayer.
(I spoke with all my friends yesterday.)
Llueve todos los días en esta ciudad.
(It rains every day in this city.)
Entendí todo lo que dijo el profesor.
(I understood everything the professor said.)
Cada
A1The word cada means each or every. It focuses on the individual members of a group, considering them one by one. Cada is invariable; it does not change for gender or number and is always followed by a noun in the singular.
Cada estudiante recibió un diploma.
(Each student received a diploma.)
Le doy a mi perro una galleta cada mañana.
(I give my dog a cookie each morning.)
El médico visita a cada paciente individualmente.
(The doctor visits each patient individually.)
Hay una cámara de seguridad en cada esquina.
(There is a security camera on each corner.)
El tren pasa por aquí cada treinta minutos.
(The train passes by here every thirty minutes.)
Cada uno debe traer su propio almuerzo.
(Each one must bring their own lunch.)
Summary
In summary, use todo when you want to talk about the entirety of a group or the whole of something (e.g., todos los perros - all the dogs). Use cada when you want to single out the individual members within a group, treating them one by one (e.g., cada perro - each dog).