Every other page in this section teaches one battleground — the past, the future, the subjunctive, the imperative. This page teaches the one decision that runs under all of them, so that when you are mid-sentence and Greek demands a stem, you have a procedure instead of a guess. Aspect is not four separate problems. It is the same question asked in four places — and once you can answer it, the four collapse into one.
The core question
Before you build any past, future, subjunctive or command form, ask yourself:
Am I seeing this action as one bounded event — or as something ongoing, repeated, or in the background?
- One bounded event you could put a full stop after → perfective stem (aorist έγραψα · θα γράψω · να γράψω · γράψε).
- Ongoing, repeated, habitual, or a background frame → imperfective stem (present γράφω · imperfect έγραφα · θα γράφω · να γράφω · γράφε).
Everything else on this page is just sharpening that one question.
Four diagnostic tests
When the core question isn't obvious, run these. Any single "yes" usually settles it.
| Ask… | If yes → |
|---|---|
| Can I put a full stop right after it? (one closed act) | perfective |
| Does it repeat as a habit / happen "every…"? (open-ended) | imperfective |
| Is it the background that something else happens during? | imperfective |
| Is it a sudden, one-moment change ("suddenly," "at once")? | perfective |
Signal words — the tells
Certain adverbs almost always travel with one aspect. They are clues, not laws (the full, honest treatment is on aspect and time adverbs), but they get you the right answer the great majority of the time.
| Pull toward imperfective | Pull toward perfective |
|---|---|
| κάθε μέρα / βδομάδα (every day/week) | χθες (yesterday, of one event) |
| συνήθως (usually), πάντα (always) | ξαφνικά (suddenly), αμέσως (at once) |
| συνέχεια (constantly), όλη μέρα (all day) | μια φορά (once), τελικά (in the end) |
| ενώ / καθώς (while, as — background) | μόλις (the moment that), πέρσι (last year) |
Ten real decisions
Watch the same question decide the aspect across every tense and mood.
1. Past — one event vs a routine. "Yesterday I cooked pasta" is one closed act (perfective aorist); "as a student I cooked every night" is a routine (imperfective imperfect).
Χθες μαγείρεψα μακαρόνια με κιμά.
chthes mayírepsa makarónia me kimá
Yesterday I cooked pasta with mince. (one act → perfective)
Όταν ήμουν φοιτητής, μαγείρευα κάθε βράδυ για όλο το σπίτι.
ótan ímun fititís, mayíreva káthe vrádhi ya ólo to spíti
When I was a student, I used to cook every night for the whole flat. (routine → imperfective)
2. Future — one purchase vs a new habit. A single gift is perfective; a lasting shopping habit is imperfective.
Θα αγοράσω ένα δώρο για τη μαμά μου το Σάββατο.
tha aghoráso éna dhóro ya ti mamá mu to Sávato
I'll buy a present for my mum on Saturday. (one act → perfective)
Από τώρα θα αγοράζω μόνο βιολογικά προϊόντα.
apó tóra tha aghorázo móno violoyiká proiónda
From now on I'll buy only organic products. (new habit → imperfective)
3. Subjunctive — one task vs a weekly duty. Clean the kitchen once (perfective); clean your room every week (imperfective).
Πρέπει να καθαρίσω την κουζίνα πριν έρθουν οι καλεσμένοι.
prépi na katharíso tin kuzína prin érthun i kalezméni
I have to clean the kitchen before the guests arrive. (one task → perfective)
Πρέπει να καθαρίζεις το δωμάτιό σου κάθε βδομάδα.
prépi na katharízis to dhomátió su káthe vdhomádha
You have to clean your room every week. (recurring → imperfective)
4. Imperative — one action vs a standing rule. Turn the light off now (perfective); always turn it off (imperfective).
Σβήσε το φως, πάμε για ύπνο.
zvíse to fos, páme ya ípno
Turn off the light, we're going to bed. (one act → perfective)
Σβήνε πάντα το φως όταν βγαίνεις από το δωμάτιο.
zvíne pánda to fos ótan vyénis apó to dhomátio
Always turn off the light when you leave the room. (standing rule → imperfective)
5. Background + event in one breath. The setting is imperfective; the thing that interrupts it is perfective.
Ενώ διάβαζα, κάποιος χτύπησε την πόρτα.
enó dhiávaza, kápios chtípise tin pórta
While I was reading, someone knocked at the door. (background → imperfective; interruption → perfective)
6. A sudden, one-moment change. "Suddenly" points at a single instant — perfective.
Ξαφνικά έσβησαν όλα τα φώτα στη γειτονιά.
ksafniká ézvisan óla ta fóta sti yitoniá
Suddenly all the lights in the neighbourhood went out.
7. A present habit. "Usually" describes a standing pattern — and the present has only the imperfective anyway.
Συνήθως πηγαίνω με τα πόδια στη δουλειά.
siníthos piyéno me ta pódhia sti dhuliá
I usually walk to work.
8. A completion at the end. "In the end" caps a single decision — perfective.
Τελικά αποφασίσαμε να μείνουμε άλλη μία μέρα.
teliká apofasísame na mínume áli mía méra
In the end we decided to stay one more day.
9. An all-day background. "All day" here frames an unbroken stretch you were inside of — imperfective.
Χθες έβρεχε όλη μέρα και δεν βγήκαμε καθόλου.
chthes évreche óli méra ke dhen vyíkame kathólu
Yesterday it rained all day and we didn't go out at all.
10. The one that trips people up — counted repetition. "Three times" is repeated, but it is a closed, counted set of completed acts, so it is perfective, not imperfective. Repetition alone does not force the imperfective; only open-ended repetition does.
Την πήρα τηλέφωνο τρεις φορές, αλλά δεν απάντησε.
tin píra tiléfono tris forés, alá dhen apándise
I called her three times, but she didn't answer. (counted, completed → perfective)
When either is genuinely possible
Be honest: some sentences accept both aspects, and the choice shifts the meaning rather than being right or wrong. "I worked all day yesterday" can be δούλεψα (a bounded whole — I put in a full day's work) or δούλευα (an unbroken stretch I was inside of). Both are natural Greek. When you hit one of these, don't hunt for the "correct" form — decide what you want to say: a packaged whole, or an ongoing process. That is the entire content of aspect, and in the grey zone it is finally visible in the open. The verbs and contexts where this happens most are gathered on imperfective vs perfective.
Common Mistakes
1. A habitual past on the aorist. "Every Christmas" is a repeated habit — imperfect, not aorist.
❌ Κάθε Χριστούγεννα μαζευτήκαμε όλοι στο σπίτι της γιαγιάς.
Incorrect — a yearly habit needs the imperfect: μαζευόμασταν.
✅ Κάθε Χριστούγεννα μαζευόμασταν όλοι στο σπίτι της γιαγιάς.
káthe Christúyena mazevómastan óli sto spíti tis yayás
Every Christmas we all gathered at grandma's house.
2. A single completion on the imperfect. "Finally finished" is one closed act — aorist.
❌ Χθες τελικά τελείωνα την αναφορά για τη δουλειά.
Incorrect — a one-time completion needs the aorist: τελείωσα.
✅ Χθες τελικά τελείωσα την αναφορά για τη δουλειά.
chthes teliká telíosa tin anaforá ya ti dhuliá
Yesterday I finally finished the report for work.
3. A repeated future on the perfective. "Every morning" is open-ended repetition — the continuous future.
❌ Θα τρέξω κάθε πρωί για να γυμναστώ λιγάκι.
Incorrect — a daily habit needs the imperfective future: θα τρέχω.
✅ Θα τρέχω κάθε πρωί για να γυμναστώ λιγάκι.
tha trécho káthe proí ya na yimnastó ligháki
I'll go for a run every morning to get a bit of exercise.
4. A standing rule on the perfective imperative. "Always lock it" is a habit — the imperfective command.
❌ Κλείδωσε πάντα την πόρτα όταν φεύγεις από το σπίτι.
Incorrect — a standing rule needs the imperfective imperative: Κλείδωνε.
✅ Κλείδωνε πάντα την πόρτα όταν φεύγεις από το σπίτι.
klídhone pánda tin pórta ótan févyis apó to spíti
Always lock the door when you leave the house.
Key Takeaways
- One question rules the whole system: one bounded event → perfective; ongoing / repeated / background → imperfective.
- The perfective feeds the aorist, θα γράψω, να γράψω, γράψε; the imperfective feeds the present, imperfect, θα γράφω, να γράφω, γράφε.
- Signal words are strong tells: κάθε/συνήθως/πάντα/όλη μέρα/ενώ → imperfective; χθες/ξαφνικά/μια φορά/τελικά/μόλις → perfective.
- The trap: counted, finished repetition ("three times") is perfective; only open-ended repetition is imperfective.
- In the grey zone, both aspects are correct — pick the viewpoint (a packaged whole vs an ongoing process) you actually mean.
Now practice Greek
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Start learning Greek →Related Topics
- Imperfective vs PerfectiveA2 — The single choice at the centre of the Greek verb: is the action a stretch you are inside of (imperfective — ongoing, repeated, habitual) or one bounded event you can put a full stop after (perfective)? A crisp two-way definition, minimal pairs across the tenses, and a map into the rest of the aspect section.
- Aspect and Time AdverbsB2 — Time adverbs correlate strongly with aspect — κάθε μέρα, συνήθως and ενώ pull imperfective; χθες, ξαφνικά and τελικά pull perfective — but they are tells, not rules. This precision page maps which adverbs force one aspect (so that swapping it is ungrammatical) and which accept both, with a shift in meaning.