Introduction
Understanding the difference between mi, tu, and su is one of the first steps for English speakers learning Spanish. These three words all translate roughly to my, your, or his/her/their in English, but they behave differently depending on formality, number, and context. This guide explains clear rules, common phrases, mistakes to avoid, and practical examples for everyday use.
- What are possessive adjectives in Spanish?
- When to use mi
- When to use tu
- When to use su
- Number agreement and plural forms
- Formal vs informal you: when to choose tu or su
- Practical scenarios and sample dialogues
- Common mistakes and how to avoid them
- Short vocabulary list and quick phrases
- Exercises for beginners
- When to use long-form possessives
- When context changes meaning
- Tips for fast learning and confidence
- Extra examples you can use right away
- Conclusion
What are possessive adjectives in Spanish?
Possessive adjectives show ownership or relationships, just like my, your, his, her, and their in English. In Spanish, possessive adjectives appear before the noun. The most common beginner forms are mi, tu, and su. Each one can refer to different owners depending on who is speaking and the level of formality.
Quick overview of mi, tu, and su
mi = used for first-person singular (I). It always matches a singular or plural noun by adding an s for plural: mi libro, mis libros.
tu = used for second-person singular informal (you, familiar). It matches number: tu casa, tus casas.
su = used for third-person singular (he/she) and third-person plural (they), and also for formal second-person (usted/ustedes). Su can mean his, her, their, your (formal). It matches number by adding s: su coche, sus coches.
When to use mi
Mi always refers to something that belongs to the speaker. It is straightforward and does not mark formality.
Examples:
mi hermano — my brother
mi trabajo — my job
mis amigos — my friends
mi teléfono está aquí — my phone is here
Practical tip: Spanish does not use an apostrophe s, so say la casa de María instead of translating directly from English as Maria’s house. For first person, use mi + noun.
When to use tu
Tu is used when speaking to someone you know well: friends, family, peers, or children. It is informal and not appropriate for strangers in formal contexts.
Examples:
tu libro — your book (talking to one familiar person)
tus zapatos — your shoes
¿Dónde está tu madre? — Where is your mother?
Tip: Do not confuse tu with tú. Tú with an accent is the subject pronoun you (informal). Tu without an accent is the possessive adjective your.
When to use su
Su is the most flexible and the most confusing for beginners because it covers several English words. Su can mean his, her, their, your (formal singular), and your (formal plural). To know which meaning, use context or add a phrase for clarity.
Examples:
su casa — his house, her house, your house (formal), or their house
sus libros — his books, her books, your books (formal), or their books
Su hijo es muy simpático — His son is very nice OR Her son is very nice OR Your son is very nice (formal)
Clarifying tip: Use de + pronoun to remove ambiguity, for example: la casa de ella (her house), la casa de él (his house), la casa de ustedes (your house plural formal/informal in many Latin American countries), la casa de ellos (their house).
Number agreement and plural forms
Possessive adjectives in Spanish must agree in number with the noun they modify, not with the possessor.
Examples:
mi amiga / mis amigas — my friend / my friends
tu coche / tus coches — your car / your cars
su mesa / sus mesas — his/her/their/your (formal) table / tables
Common mistake: Beginners sometimes try to change possessive form to match the owner: do not say *mis yo*. Always change the noun: mis libros, not *mi libros*.
Formal vs informal you: when to choose tu or su
Spanish distinguishes between informal you and formal you. Use tu for informal one-on-one situations. Use su for formal interactions with strangers, elders, or in professional contexts.
Examples:
If speaking to a friend: ¿Dónde está tu bolsa?
If speaking to a client or elder: ¿Dónde está su bolsa?
Note: In many parts of Latin America, the informal plural you is ustedes, and the possessive is su or sus. This means su also serves for this plural usage and can be ambiguous without context.
Practical scenarios and sample dialogues
Ordering at a cafe:
Quisiera mi café con leche, por favor.
¿Y tu sándwich? — ¿Quieres compartir tu sándwich?
At work or a bank (formal):
¿Puede traerme su identificación, por favor?
Speaking about friends:
Sus nombres son Carlos y Ana. — Their names are Carlos and Ana.
Talking about family:
Mi mamá trabaja temprano. — My mom works early.
Common mistakes and how to avoid them
Mistake 1: Confusing tu and tú. Remember: tu is possessive; tú is the pronoun.
Example error: *Tú casa está aquí.* Correct: tu casa está aquí.
Mistake 2: Using su without context and causing ambiguity. If meaning matters, add clarification.
Ambiguous: su coche está afuera. Clear: el coche de ella está afuera. OR el coche de ellos está afuera.
Mistake 3: Forgetting plural agreement. Use mis, tus, sus when the noun is plural.
Wrong: mi amigos. Right: mis amigos.
Short vocabulary list and quick phrases
mi libro — my book
mis libros — my books
tu llave — your key (informal)
tus llaves — your keys
su puerta — his/her/your (formal)/their door
sus puertas — his/her/your (formal)/their doors
la casa de él — his house
la casa de ella — her house
la casa de ellos — their house
Exercises for beginners
Replace the English possessive with the correct Spanish form:
1) My mother = _______ madre
2) Your (informal) phone = _______ teléfono
3) Their friends = _______ amigos
4) Your (formal) appointment = _______ cita
Answers: 1) mi madre 2) tu teléfono 3) sus amigos 4) su cita
When to use long-form possessives
Spanish also has long-form possessives that come after the noun and agree in gender and number: mío, tuyo, suyo, nuestro, vuestro, suyo. These are useful for emphasis or clarity.
Examples:
Es mi libro — This is my book.
El libro es mío — The book is mine.
Su casa es grande, pero la casa de ellos es más grande — Their house is big, but their house (of them) is bigger. Use long form for strong contrast or clarity.
Note: For beginners, focus first on short possessives mi, tu, su before learning all long-form variants.
When context changes meaning
Because su covers several English possessives, context decides meaning. Think about who is speaking and who is being referred to.
Example 1: Ella busca su libro. — She looks for her book.
Example 2: Usted busca su libro. — You (formal) look for your book.
Example 3: Ellos buscan su libro. — They look for their book.
If you overhear a sentence and are unsure, ask a short clarifying question: ¿De quién es? — Whose is it?
Tips for fast learning and confidence
Practice everyday phrases: label items at home with sticky notes: mi mesa, mi silla, mi puerta. This builds automatic associations.
Listen for context: when native speakers use su, try to infer whether they mean his, her, or their. If unsure, ask or look for surrounding clues.
Use clarification phrases: el libro de ella, el coche de él, la casa de ellos.
Remember the rules in short form: mi = my, tu = your (informal), su = his/her/their/your (formal). Add s for plurals on the noun, not on the possessor word.
Extra examples you can use right away
mi clave es 1234 — my password is 1234
¿Dónde está tu boleto? — Where is your ticket?
Por favor, entregue su formulario en la recepción — Please hand your form at reception (formal)
Ellos dijeron que su vuelo llega a las 10 — They said their flight arrives at 10
Conclusion
Mastering mi, tu, and su is essential for basic Spanish conversation. Start with the simple rule: mi = my, tu = your informal, su = his/her/their/your formal. Pay attention to number agreement, use clarifying phrases when su is ambiguous, and practice with real-life labels and short dialogues. With focused practice and the examples above, you will use these possessives confidently in everyday Spanish.
