Saber

Saber means to know — but specifically to know facts, information, and how to do things, as opposed to conhecer, which means to be acquainted with people and places. It is one of the most irregular verbs in the language, with surprises in nearly every tense: the present sei, the preterite soube, the present subjunctive saiba, and the future subjunctive souber. Because it is so frequent and so irregular, it rewards memorizing the four "anchor" forms and building outward from them. This page lays out the full paradigm and then the all-important contrast with conhecer and the saber + infinitive construction.

The four anchor forms

Most of saber's irregularity radiates from four forms. Learn these and the rest falls into place:

1. Present eu = sei (not the expected sabo).
2. Preterite eu/ele = soube — the whole preterite uses the irregular stem soub-.
3. Present subjunctive = saiba — the whole present subjunctive uses the stem saib-.
4. Future subjunctive = souber — built, like all future subjunctives, on the preterite stem soub-.

Presente do indicativo

Only the eu form is irregular (sei); everything else uses the regular stem sab-.

Pretérito perfeito

The entire preterite is built on the irregular stem soub-, with the strong (rhizotonic) endings shared by other irregular preterites like pude/pôde and coube. Crucially, soube here often means found out / learned rather than the static "knew."

Pretérito imperfeito

The imperfect is perfectly regular (stem sab- + -ia). Use it for the ongoing state of knowing — the default "knew" in narration.

Futuro do presente & futuro do pretérito (conditional)

Both are built on the full infinitive saber-, so they are regular.

In speech the simple future is usually replaced by ir + infinitive: vou saber rather than saberei. (informal)

Presente do subjuntivo

The whole present subjunctive uses the irregular stem saib-. There is no shortcut — it is simply memorized.

Imperfeito & futuro do subjuntivo

Both are built on the preterite stem soub-. The imperfect subjunctive adds -esse; the future subjunctive adds -er.

Imperativo

The affirmative tu form (sabe) is from the present indicative; você/vocês and all negatives use the subjunctive stem saib-. In practice, commanding someone "to know" is rare and usually means be aware.

Non-finite forms

All regular.

saber vs. conhecer — the central distinction

English uses to know for everything. Portuguese splits the job:

• saber = to know a fact, a piece of information, or how to do something. It takes facts, embedded questions (saber que, saber onde, saber se, saber quem), and infinitives of ability.
• conhecer = to be acquainted with a person, place, or thing through direct experience. It takes a plain noun object and never a clause.

The reliable test: if the object is a clause or an infinitive, you need saber; if it is a person, place, or thing you've experienced, you need conhecer.

saber + infinitive = to know how to

This is the standard way to express a skill or ability. There is no "como" in between — that is an English-influenced error.

Common Mistakes

False-friend warning

In Brazil, saber also describes taste: saber a/de = to taste of/like something — but this usage is far more common in European Portuguese ("Isto sabe a limão" = "This tastes of lemon"). In Brazil you would normally say "tem gosto de limão." (regional: PT-PT) Don't confuse this with the core meaning to know.

Key Takeaways

• Drill the four anchors: sei / soube / saiba / souber.
• soube = found out (a moment); sabia = already knew (a state).
• saber is for facts, clauses, and skills (saber + infinitive); conhecer is for people and places.
• After future-time conjunctions like quando and se, use the future subjunctive souber.
• "Know how to" is saber + infinitive with no como in between.