Demasiado is a common adjective or adverb that usually carries the idea of "too," "too much," "too many," "excessive" or "excessively."
When used as an adjective, demasiado precedes the noun it refers to and agrees in number and gender with it. Demasiado can also appear in the predicate of a sentence following a form of ser.
- Tres partidos políticos son demasiados. Three political parties are too many.
- Hay demasiado azúcar en los cereales de los niños. There is too much sugar in children's cereals.
- Fue demasiada la tentación. The temptation was too much.
- Tener demasiados amigos en Facebook provoca estrés y culpa. Having too many friends on Facebook causes stress and guilt.
- ¿Se puede tener demasiado amor, demasiada fe o demasiada honestidad? Considero que no. Can one have too much love, too much faith or too much honesty? I think not.
As an adverb, demasiado is invariable - that is, it doesn't change in form. It typically comes before any adjective or adverb it affects the meaning of but after any such verb.
- El verano llegó demasiado rápido. Summer arrived too quickly.
- El expresidente habla demasiado y sus declaraciones son desatinadas. The former president talks too much and his statements are foolish.
- Dicen que los coches ecológicos son demasiado caros. They say "green" cars are too expensive.
- Soy demasiado inteligente para creer en esas cosas. I'm too smart to believe in those things.
- Las áreas brillantes pueden aparecer demasiado blancas en las fotos. Bright areas can seem too white in the photos.
- El problema es que mi marido trabaja demasiado. The problem is that my husband works too much.
In popular speech, you may sometimes hear demasiado as an adverb made to agree with an adjective it refers to, but this is not considered grammatically proper Spanish. As an exception to the rule, however, it is correct to make demasiado agree with forms of poco: Pasan demasiadas cosas en demasiadas pocas páginas. Too many things happen in too few pages.
Sample sentences are adapted from a variety of sources. Among those used in preparaing this lesson: Tiempo (Honduras), ABC (Spain), San-Pablo.com.ar, Bogo de la web, Actualidad Motor, Reina del Cielo, Ideeleradio, Sony.es, ForoAmor.com, Cinemascope.