Spanish Phrase
Una entra, una sale.
Meaning
Literally, 'one goes in, one goes out.' It is used to express the idea that for every gain there is a loss, or that a system stays in equilibrium by replacing what is taken with something else.
When to use
Use this expression when you want to stress fairness, balance, or a rotating system – for example, in shift work, inventory control, sports line‑ups, or even in everyday talk about sharing responsibilities.
✦Grammar Breakdown
unaentraunasale
Indefinite article (una)
Una is the feminine singular indefinite article, used here as a pronoun meaning 'one' or 'something'.
Entrar (present 3rd‑person singular)
Entra is the present‑indicative form of entrar for él/ella/usted, meaning 'enters' or 'goes in'.
Salir (present 3rd‑person singular)
Sale is the present‑indicative form of salir for él/ella/usted, meaning 'exits' or 'goes out'.
Parallel structure
The phrase repeats the same grammatical pattern (una + verb) to create a balanced, rhythmic idiom.
🗨In Conversation
¿Quién hará la noche de guardia?
Who will take the night shift?
Una entra, una sale. Tú lo hiciste la semana pasada, ahora me toca a mí.
One goes in, one goes out. You did it last week, now it's my turn.
✕Common Mistakes
uno entra, una sale
The article must agree with the implied noun; using 'uno' (masc.) with 'entra' breaks the parallelism.
entra y sale
Leaving out the indefinite article loses the idiomatic punch and sounds like a simple statement rather than a rule.
la una entra, la una sale
Do not add an extra 'la' (e.g., 'la una entra') – the phrase works without a definite article.
↔Alternatives
Lo que entra, sale.
What goes in, comes out.
Una entra, otra sale.
One enters, another exits.
Todo tiene su salida.
Everything has its exit.
Cultural Tip
The phrase is common in Spanish‑speaking workplaces and sports teams to remind people about rotation and fairness. It carries a neutral, informal register, so it fits well in casual conversation but would sound out of place in a formal report. In some regions, people also say "uno entra, otro sale" to stress the idea of different people swapping places.