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
When the verb supplies both aspectual stems in the intended meaning, ask yourself:
Am I packaging the situation — one occurrence or a finite series — as a bounded whole, or viewing it from inside as a process, open habit, or background?
- A bounded whole, including a finite or delimited repeated series → perfective stem (aorist έγραψα · θα γράψω · να γράψω · γράψε).
- An internal process or state, open-ended habit, or background frame → imperfective stem (present γράφω · imperfect έγραφα · θα γράφω · να γράφω · γράφε). A single event can therefore be imperfective when you view it from inside.
Everything else on this page is just sharpening that one question.
First confirm that there really is a pair to choose from. Basic είμαι, έχω, and ξέρω do not have same-lexeme perfective partners in their stative meanings. γίνω, αποκτήσω, and μάθω express changes of state, not simply “the other aspect” of those verbs. Do not invent a missing stem.
The decision flow
Run this sequence rather than counting events or matching an adverb mechanically.
| Step | Ask… | Route |
|---|---|---|
| 0 | Does this verb and meaning supply both stems? | No: use the available form or another lexeme. Yes: continue. |
| 1 | Am I packaging an occurrence or finite series within a contextual boundary? | perfective |
| 2 | Am I presenting an internal process or state, an open habit, or background? | imperfective |
| 3 | Could either viewpoint fit the situation? | Choose the construal you intend; use adverbs only as contextual evidence. |
Signal words — the tells
Certain adverbs often suggest a viewpoint. They are clues, not laws — several combine naturally with either aspect when the context changes — and the full treatment is on aspect and time adverbs.
| Pull toward imperfective | Pull toward perfective |
|---|---|
| κάθε μέρα / βδομάδα (every day/week) | χθες + a bounded episode (yesterday) |
| 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 as a delimited whole (last year) |
Ten real decisions
Watch the same question decide the aspect across every tense and mood.
1. Past — bounded episode vs open routine. Here “yesterday” helps package the pasta-cooking episode as a bounded whole (perfective aorist); the student-years frame presents cooking as an open routine (imperfective imperfect).
Χθες μαγείρεψα μακαρόνια με κιμά.
chthes mayírepsa makarónia me kimá
Yesterday I cooked pasta with mince. (bounded episode → 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. (open routine → imperfective)
2. Future — bounded purchase vs new open habit. The gift purchase is contextually bounded by its object and Saturday; the lasting shopping policy is presented as open-ended.
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. (bounded purchase → 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 — bounded task vs standing duty. The kitchen is presented as a task to complete within a contextual boundary; the weekly room-cleaning is an open obligation.
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. (bounded 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. (open obligation → imperfective)
4. Imperative — bounded instruction vs standing rule. The immediate request packages switching off as a bounded task; the general rule leaves the conduct open across occasions.
Σβήσε το φως, πάμε για ύπνο.
zvíse to fos, páme ya ípno
Turn off the light, we're going to bed. (bounded instruction → 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 change presented as a whole. In this context, "suddenly" helps bound the change — 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 decision packaged at the endpoint. Here “in the end” closes the decision as a bounded whole — 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 — a finite repeated series. "Three times" here falls inside one closed past episode, so the speaker packages the series as a bounded whole. Repetition alone does not force the imperfective; an open-ended series does favor it.
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. (finite, delimited series → 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. Treating all repetition alike. An open childhood custom is imperfective; a finite run of three Christmases can be packaged perfectively.
✅ Τρία συνεχόμενα Χριστούγεννα μαζευτήκαμε όλοι στο σπίτι της γιαγιάς.
tría sinechómena Christúyena mazeftíkame óli sto spíti tis yayás
For three Christmases in a row, we all gathered at grandma's house. (finite series → perfective)
✅ 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. Assuming one real-world event must be perfective. The imperfective can place you inside one report-writing episode; the aorist packages it as a bounded whole.
✅ Χθες το απόγευμα τελείωνα την αναφορά όταν χτύπησε το τηλέφωνο.
chthes to apóyevma telíona tin anaforá ótan chtípise to tiléfono
Yesterday afternoon I was finishing the report when the phone rang. (one event viewed internally → imperfective)
✅ 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. Letting repetition alone choose the future. An open routine is imperfective; a delimited set of calls can be perfective.
✅ Αύριο θα τον πάρω τηλέφωνο τρεις φορές.
ávrio tha ton páro tiléfono tris forés
Tomorrow I'll call him three times. (delimited series → perfective)
✅ Από δω και πέρα θα τον παίρνω τηλέφωνο κάθε πρωί.
apó dho ke péra tha ton pérno tiléfono káthe proí
From now on I'll call him every morning. (open routine → imperfective)
4. Ignoring the viewpoint in a command. The imperfective gives a standing rule; the perfective packages the immediate instruction as bounded.
✅ Κλείδωσε την πόρτα πριν φύγεις.
klídhose tin pórta prin fíyis
Lock the door before you leave. (bounded instruction → perfective)
✅ 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: a bounded occurrence or finite series → perfective; an internal process, open habit, or 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 clues, not controllers: ask whether they create a contextual boundary or an open/internal frame.
- The trap: a finite or delimited series can be perfective; open-ended repetition favors the imperfective, and a count by itself settles nothing.
- In the grey zone, both aspects are correct — pick the viewpoint (a packaged whole vs an ongoing process) you actually mean.
- The procedure chooses between existing stems; some stative or defective verbs do not supply the contrast in a given meaning.
Related Topics
- Imperfective vs PerfectiveA2 — The central Greek aspect choice: an internal or unbounded view (imperfective) versus an event or finite series packaged as one bounded whole (perfective). Event count and English tense are clues, never mechanical rules.
- Aspect and Time AdverbsB2 — Time adverbs strongly cue an aspectual viewpoint but never select it mechanically: every, suddenly and constantly can combine with different aspects when the time horizon, lexical meaning or scope changes.
- Imperfect vs AoristB1 — Use one compact decision flow to choose an internal or open past viewpoint versus an occurrence or finite series packaged as bounded.