Dever is a small word that carries three big jobs: it expresses obligation (should, ought to), probability (must, is probably), and the very concrete sense of owing money or a favor (to owe). It is morphologically a completely regular -er verb, so the conjugation gives you no trouble — the difficulty is entirely in choosing the right meaning. English splits these jobs across three different expressions ("should," "must," "owe"), so the main work for an English speaker is learning that one Portuguese verb covers all three.
Why one verb means three things
The link between "should," "must (probably)," and "owe" is not random. At its core, dever expresses a kind of debt: something is owed. With money, the debt is literal — you owe fifty reais. With obligation, the debt is moral — you ought to do something, as if you owed it. With probability, the debt is logical — the evidence "owes" you a conclusion, so something must be the case. English actually preserves a trace of this: "you should" and "you owe it to yourself" share the same Germanic root (shall/should once meant "to owe"). Seeing dever as "debt of some kind" makes all three senses feel like one idea.
Presente do indicativo
| Pronoun | Form |
|---|---|
| eu | devo |
| tu | deves |
| você / ele / ela | deve |
| nós | devemos |
| vocês / eles / elas | devem |
Perfectly regular: stem dev- plus the standard -er endings. There is no stem change and no spelling trick.
Você deve descansar mais, está com cara de cansado.
You should rest more, you look tired.
Deve estar chovendo lá fora, o pessoal chegou todo molhado.
It must be raining outside, everyone came in soaked.
Pretérito perfeito
| Pronoun | Form |
|---|---|
| eu | devi |
| tu | deveste |
| você / ele / ela | deveu |
| nós | devemos |
| vocês / eles / elas | deveram |
The preterite is most natural in the "owe" sense ("I owed him money") or as a past probability. As with all -er verbs, devemos is identical in the present and the preterite — context decides.
Eu devi uma boa quantia pro meu irmão até quitar tudo no ano passado.
I owed my brother a good sum until I paid it all off last year.
Pretérito imperfeito
| Pronoun | Form |
|---|---|
| eu | devia |
| tu | devias |
| você / ele / ela | devia |
| nós | devíamos |
| vocês / eles / elas | deviam |
This is a workhorse form. In everyday Brazilian speech, devia is the normal way to say "should have" or a softened "should" — much more common than the conditional deveria. "Você devia ter me avisado" = "You should have told me." (informal)
Você devia ter me avisado que a reunião mudou de horário.
You should have told me the meeting time changed.
Eu devia mil reais pro banco, mas já paguei quase tudo.
I owed the bank a thousand reais, but I've already paid almost all of it.
Futuro do presente & futuro do pretérito (conditional)
Both are built on the full infinitive dever-.
| Pronoun | Futuro do presente | Futuro do pretérito |
|---|---|---|
| eu | deverei | deveria |
| tu | deverás | deverias |
| você / ele / ela | deverá | deveria |
| nós | deveremos | deveríamos |
| vocês / eles / elas | deverão | deveriam |
The conditional deveria is the "textbook" polite "should." In writing and careful speech it is the standard; in casual speech Brazilians frequently swap it for the imperfect devia. The future deverá is common in formal registers for predictions and mild obligations ("the candidate must present the documents"). (formal)
O candidato deverá apresentar os documentos até sexta-feira.
The candidate must submit the documents by Friday.
Você deveria pensar melhor antes de aceitar essa proposta.
You ought to think it over before accepting that offer.
Presente do subjuntivo
-er verbs take -a endings in the present subjunctive.
| Pronoun | Form |
|---|---|
| eu | deva |
| tu | devas |
| você / ele / ela | deva |
| nós | devamos |
| vocês / eles / elas | devam |
Talvez ele deva uma explicação pra gente depois de tudo isso.
Maybe he owes us an explanation after all of this.
Imperfeito & futuro do subjuntivo
| Pronoun | Imperfeito do subjuntivo | Futuro do subjuntivo |
|---|---|---|
| eu | devesse | dever |
| tu | devesses | deveres |
| você / ele / ela | devesse | dever |
| nós | devêssemos | devermos |
| vocês / eles / elas | devessem | deverem |
Se eu devesse a alguém, pagaria na hora.
If I owed someone, I'd pay them right away.
Imperativo
The imperative of dever is rare — you don't usually command someone to "owe" or to "be probable." When it appears, it follows the regular pattern.
| Pronoun | Afirmativo | Negativo |
|---|---|---|
| tu | deve | não devas |
| você | deva | não deva |
| nós | devamos | não devamos |
| vocês | devam | não devam |
Non-finite forms
| Form | Result |
|---|---|
| Infinitivo | dever |
| Infinitivo pessoal (eu / você / ele) | dever |
| Infinitivo pessoal (nós) | devermos |
| Infinitivo pessoal (vocês / eles) | deverem |
| Gerúndio | devendo |
| Particípio | devido |
Note that dever is also a noun: o dever = "duty" (and os deveres / a lição de casa = "homework"). The participle devido doubles as a preposition: devido a = "due to / because of."
The three meanings in detail
1. Obligation — should / ought to
Always dever + infinitive. This is a softer obligation than ter que ("have to"). "Você deve estudar" advises; "Você tem que estudar" pressures.
A gente deve respeitar quem trabalha duro.
We ought to respect people who work hard.
2. Probability — must (a confident guess)
Also dever + infinitive, but now it's a deduction, not a command. Often paired with estar + gerund: deve estar = "must be (-ing)."
Ela não atende o celular — deve estar dormindo a essa hora.
She's not answering her phone — she must be sleeping at this hour.
3. Owing — to owe
Here dever takes a direct object (the thing owed) and a for the person: dever (algo) a (alguém).
Eu te devo um café pela força que você me deu ontem.
I owe you a coffee for the help you gave me yesterday.
Common Mistakes
❌ Eu devo de estudar mais.
Incorrect — no 'de' between dever and the infinitive.
✅ Eu devo estudar mais.
I should study more.
❌ Eu devo dinheiro para você → 'dever para'.
Less natural — the owing sense uses 'a' (or the clitic te), not 'para'.
✅ Eu devo dinheiro a você. / Eu te devo dinheiro.
I owe you money.
❌ Você deve a estudar.
Incorrect — that's a calque of Spanish 'deber de'; Portuguese is just dever + infinitive.
✅ Você deve estudar.
You should study.
❌ Deve ser tarde → meaning 'I owe'.
Confusing the senses — 'deve ser tarde' means 'it must be late' (probability), not owing.
✅ Devo a ele um favor.
I owe him a favor.
❌ Eu deveria de ter ido.
Incorrect — drop the 'de'; it should be deveria ter ido.
✅ Eu deveria ter ido. / Eu devia ter ido.
I should have gone.
Key Takeaways
- Dever is a fully regular -er verb — no stem changes, no irregular forms.
- One verb covers should (obligation), must (probability), and owe (debt); context disambiguates.
- For "should," use devia (casual) or deveria (careful) — both common in Brazil.
- Never insert de before the infinitive: it's dever + infinitive, not dever de (that's Spanish).
- Compare with ter que for stronger obligation.
Now practice Portuguese
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Portuguese→Related Topics
- Ter que + Infinitivo / Dever + Infinitivo (Obligation)A2 — How Brazilian Portuguese expresses obligation and necessity — ter que, ter de, dever, and precisar plus an infinitive.
- PrecisarA1 — The regular -ar verb 'precisar' (to need), with the crucial 'precisar de + noun' construction, the BR habit of dropping 'de' before an infinitive ('Preciso sair'), and the formal sense 'to specify'.
- PoderA1 — How to conjugate and use poder (can / may / to be able to) in Brazilian Portuguese — a highly irregular -er verb — including the circumflex on pôde, the meaning split between pude (managed to) and podia (was able to), and the everyday phrase pode ser.
- ComerA1 — How to conjugate and use comer (to eat) in Brazilian Portuguese — the model regular -er verb — plus key idioms and a register note on its slang sense.
- Present Indicative: Regular -er VerbsA1 — How to conjugate regular -er verbs in the Brazilian Portuguese present indicative — and why so many common -er verbs are irregular.