Possessive pronouns and stressed possessives

What it is

Besides mi, tu, su before a noun, Spanish has stressed possessives: mío, tuyo, suyo, nuestro. You use them on their own (Es mío), with an article instead of a noun (la mía) and after a noun (un amigo mío).

How to form it

They agree with the thing owned, in gender and number, like adjectives:

(Vuestro, vuestra is the form for vosotros, used in Spain.)

When to use it

• After ser, to say who owns something: —¿De quién es esta chaqueta? —Es mía.
• With an article, as a pronoun, so you don't repeat the noun: Tu casa es más grande que la mía. Mi celular no tiene batería, ¿me prestas el tuyo?
• After a noun, for "a … of mine": un amigo mío, una idea suya. Also in set phrases: ¡Dios mío!

• —¿De quién es esta chaqueta? —Es mía.—Whose jacket is this? —It's mine.after ser
• Esta no es mi maleta; la mía es azul.This isn't my suitcase; mine is blue.la mía
• Un amigo mío vive en Rosario.A friend of mine lives in Rosario.after a noun

Contrasts and traps

• Before the noun: the short form, with no article: mi casa, not la mía casa.
• After ser: the stressed form: Es mío, not Es mi.
• Agreement is with the thing, not the owner: Las llaves (de Juan) son suyas.
• Suyo can mean his, hers, yours (usted) or theirs. If it's unclear, say de él, de ella, de ustedes: Es de ella.

If you also speak Portuguese

Very close to Portuguese: o meu → el mío, um amigo meu → un amigo mío, É meu → Es mío. The big difference is before a noun: Portuguese a minha casa is just mi casa in Spanish, with no article.