Preterite vs Imperfect Overview | Portuguese (Portugal) Grammar

Portuguese has two simple past tenses, and choosing between them is the single biggest hurdle English speakers face when they move past the present. English gets by with one all-purpose past (I ate, I was eating, I used to eat all happily coexist under the same -ed ending), but Portuguese forces a choice every time: was the action a closed package (pretérito perfeito simples, usually just called the preterite) or an open window into the past (pretérito imperfeito, the imperfect)? The choice is not about when something happened. It is about how the speaker is looking at it.

Aspect, not tense

The technical word for what is going on here is aspect. Tense tells you when — past, present, future. Aspect tells you how an action unfolds in time — as a bounded event, or as a situation stretched over a period. English has tense but only a weak sense of aspect in its simple past. Portuguese, like Spanish, French, and Italian, splits the past into two distinct aspects, and you cannot escape picking one.

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The question is never "did this happen in the past?" — both tenses answer yes. The question is "am I viewing this as a finished event or as an ongoing situation?" That is the entire game.

The two lenses

Think of the preterite and imperfect as two different camera lenses pointed at the same past. The preterite is the shutter click: one snap, one finished event, frame closed. The imperfect is a wide, slow pan: the scene, the weather, the habits, what was going on in the background while other things happened.

Ontem fui ao supermercado.

Yesterday I went to the supermarket.

Quando era miúdo, ia ao supermercado com a minha avó à sexta-feira.

When I was a kid, I'd go to the supermarket with my grandma on Fridays.

Same verb (ir, to go), same physical action, completely different stories. The first is one closed trip. The second is a childhood routine that has no start or end in the speaker's mind — just a recurring pattern. Fui is a snapshot; ia is a long exposure.

What the preterite does

The pretérito perfeito simples expresses an action viewed as a whole, completed unit. It has a boundary — explicit or implied — and the speaker is treating it as done, wrapped up, accounted for.

Use it for:

Single completed actions (comprei um bilhete)
Sequences of events that push a story forward (cheguei, vi, saí)
Actions pinned to a specific moment or period (em 2019 mudei-me para o Porto)
Defined durations that have finished (estive dois anos em Coimbra)

Ontem à noite o Pedro telefonou-me três vezes.

Last night Pedro called me three times.

Acordei às sete, tomei um duche e saí para o trabalho.

I woke up at seven, took a shower, and left for work.

Estive doente a semana passada, mas já estou melhor.

I was sick last week, but I'm better now.

Every verb above is a closed package. You can almost hear the lid click shut. Três vezes is a countable three calls; da semana passada is a bounded chunk of time with a start and an end.

What the imperfect does

The pretérito imperfeito expresses an action or state without boundaries — ongoing, habitual, or descriptive. The speaker is not saying it ended; the speaker is not saying it began. It is just how things were, over some stretch of past time.

Use it for:

Habitual or repeated actions in the past (ia à praia todos os verões)
Descriptions of scenes, weather, appearance, feelings (a casa era grande, fazia frio)
Ongoing actions serving as background (ela lia quando bateram à porta)
Ages, times, and states that stretch over a period (tinha dez anos; eram oito da noite)

Quando vivíamos em Évora, o meu pai trabalhava no banco e eu andava numa escola pequena.

When we lived in Évora, my dad worked at the bank and I went to a small school.

Eram quase nove da noite e ainda estava calor.

It was nearly nine at night and it was still hot.

Naquela altura, a minha avó fazia sempre bolo ao domingo.

Back then, my grandmother always made cake on Sundays.

Notice that none of these sentences tells you when the situation started or ended. They describe the past as something one could walk around inside.

The English trap

English flattens this distinction, which is exactly why it trips up learners. A single English sentence like I lived in Lisbon can map to either Portuguese tense depending on what the speaker has in mind:

Vivi em Lisboa dois anos. — "I lived in Lisbon for two years." (Closed, bounded period → preterite.)
Vivia em Lisboa quando aconteceu. — "I was living in Lisbon when it happened." (Ongoing situation at the time → imperfect.)

Trabalhei na Google durante três anos.

I worked at Google for three years. (Finished, defined stretch → preterite.)

Na altura, trabalhava na Google e vivia em Londres.

At the time, I was working at Google and living in London. (Ongoing background → imperfect.)

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A shortcut from English: if you could naturally say "was —ing" or "used to," you almost certainly want the imperfect. If you could naturally say "did" with a time boundary, you want the preterite. It is not bulletproof, but it catches most cases.

A first decision framework

Before you conjugate, ask two short questions:

Is this one finished event (or a defined chunk) — or is it a description, habit, or ongoing situation?
Does it move the story forward, or does it tell me what was going on while other things happened?

Finished event or forward motion → preterite. Description, habit, ongoing state, or background → imperfect.

Ela estudava medicina quando conheceu o marido.

She was studying medicine when she met her husband.

In this one sentence you see both tenses doing their jobs. Estudava is the ongoing background — she was in the middle of a multi-year degree. Conheceu is the single event that actually happened — one afternoon, one meeting. The imperfect sets the stage; the preterite delivers the news.

In real Portuguese, the preterite and imperfect rarely appear alone. A typical past paragraph weaves them together: the imperfect paints the scene, the preterite reports the events that break into it. This interleaving is so characteristic of Portuguese narration that natives do it without thinking.

Era domingo de manhã e chovia imenso. Eu estava a ler no sofá quando alguém tocou à campainha. Levantei-me, fui até à porta e abri. Era o meu irmão, que vinha sem guarda-chuva e estava completamente molhado.

It was Sunday morning and it was pouring with rain. I was reading on the sofa when someone rang the doorbell. I got up, went to the door, and opened it. It was my brother, who was coming without an umbrella and was completely soaked.

Count the tenses. Era, chovia, estava a ler, vinha, estava — imperfects for setting, weather, ongoing actions, states. Tocou, levantei-me, fui, abri — preterites for the events that happened in sequence. Pull out either layer and the paragraph collapses: only events gives you a dry police report; only background gives you a mood piece with nothing happening.

Why English speakers mis-tense

The three most common mistakes come from applying English habits:

Mistake 1: using preterite for habitual past. English "I went to the beach every summer" feels like a simple past, so learners reach for fui. But "every summer" makes it habitual — Portuguese demands the imperfect.

Mistake 2: using imperfect for bounded duration. English "I lived in Porto for two years" sounds ongoing, but the two years closes the box. Portuguese wants the preterite.

Mistake 3: using preterite for background descriptions. English "It was a cold day" describes a state. Portuguese learners often pick foi, but descriptions of how things were overwhelmingly take the imperfect: era um dia frio.

All three come from the same root: English hides aspect, so speakers never learned to mark it. Portuguese makes you mark it every time.

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Do not expect this to click overnight. Intermediate learners wrestle with preterite versus imperfect for months, sometimes years. Reading and listening to real Portuguese stories is the fastest way to internalize the rhythm.

Quick-reference cheat sheet

The action is...	Preterite	Imperfect
A single completed event	yes	—
A habit or repeated routine	—	yes
A description (weather, age, scene)	—	yes (usually)
Ongoing at the time of something else	—	yes
The interruption that breaks in	yes	—
A defined duration (dois anos, três horas)	yes	—
An undefined stretch (naquela altura)	—	yes
A sequence pushing the story forward	yes	—
A state or feeling over a period	—	yes
A change of state (met, found out, managed)	yes	—

Common Mistakes

❌ Quando era criança, fui à praia todos os verões.

Incorrect — habitual past requires the imperfect, not the preterite.

✅ Quando era criança, ia à praia todos os verões.

When I was a child, I'd go to the beach every summer.

❌ Ontem ia ao supermercado e comprava pão.

Incorrect — these are single completed actions with a time anchor (ontem).

✅ Ontem fui ao supermercado e comprei pão.

Yesterday I went to the supermarket and bought bread.

❌ Foi um dia frio e havia muito vento.

Incorrect — 'foi' closes the day; general description of weather wants the imperfect throughout.

✅ Era um dia frio e havia muito vento.

It was a cold day and there was a lot of wind.

❌ Vivia em Londres três anos.

Incorrect — a bounded, defined duration (três anos) requires the preterite.

✅ Vivi em Londres três anos.

I lived in London for three years.

❌ Quando ela chegava, eu já jantei.

Incorrect — the punctual event (she arrived) should be preterite; the background state of 'having already eaten' wants pluperfect, not preterite.

✅ Quando ela chegou, eu já tinha jantado.

When she arrived, I had already had dinner.

Key takeaways

Portuguese past tense is a question of aspect, not just time. Both tenses are past; they disagree about how the past is viewed.
Preterite = closed, bounded, completed, foreground. The story's events.
Imperfect = open, unbounded, descriptive, habitual, background. The story's setting.
Most real past sentences in Portuguese use both tenses together. Learning to weave them is what sounds native.
If your English translation wants "used to" or "was —ing," reach for the imperfect; if it wants "did" with a time stamp, reach for the preterite.