English packs every kind of obligation into a tiny handful of words — must, have to, should, need to, ought to — and leaves you to guess from context whether the pressure comes from inside (a sense of duty), from circumstances (you had no choice), or from a rule. Russian refuses to flatten all of that. It offers a graded set of expressions that differ in two things at once: the grammar they demand (some take a nominative subject, most take a dative experiencer) and the kind of force they convey (moral duty, practical need, external compulsion, formal obligation, advice). Picking the right one tells your listener why you are doing the thing — a nuance English simply drops. This page lays the whole spectrum out from strongest to softest, with the past, the future, and the negatives of each.
This is the depth page; for the core grammatical split between agreeing до́лжен and impersonal на́до/ну́жно start with должен, надо, нужно.
The spectrum at a glance
The single most useful thing to carry away is the ordered ladder. Read it top to bottom as "most forceful / most formal" down to "merely advisable".
| Expression | Force | Subject case | Register | Rough English |
|---|---|---|---|---|
| нельзя́ + inf | prohibition (the floor) | dative | neutral | must not / may not |
| обя́зан | binding obligation | nominative (agrees) | formal / emphatic | am obliged / duty-bound |
| прихо́дится / пришло́сь | forced by circumstance | dative | neutral | have to (no choice) |
| вы́нужден | compelled, against one's will | nominative (agrees) | formal | am forced to |
| до́лжен | personal duty / expectation | nominative (agrees) | neutral | must / should |
| на́до / ну́жно + inf | practical necessity | dative | neutral (на́до a touch colloquial) | need to |
| сле́дует + inf | advisable, proper | dative | formal | ought to / one should |
| сто́ит + inf | worth doing | dative | neutral | it's worth -ing |
обя́зан — binding obligation
обя́зан ("obliged, duty-bound, am required") is stronger than до́лжен. It frames the obligation as something you are formally or morally bound to — by a contract, a law, your role, or a debt of conscience. Like до́лжен it is a short adjective with a nominative subject, agreeing in gender and number: обя́зан / обя́зана / обя́заны.
Ка́ждый граждани́н обя́зан плати́ть нало́ги.
Every citizen is obliged to pay taxes. — обя́зан frames it as a legal duty, stronger and more formal than до́лжен.
Я вам о́чень обя́зан за по́мощь.
I'm much obliged to you for your help. — with за + accusative, обя́зан also means 'indebted, grateful'.
Врачи́ обя́заны сообща́ть о таки́х слу́чаях.
Doctors are obliged to report such cases. — a professional/legal requirement (plural обя́заны).
The difference from до́лжен is one of weight. Я до́лжен позвони́ть is "I should / need to call"; Я обя́зан позвони́ть is closer to "I am duty-bound to call — it would be wrong not to."
вы́нужден — compelled against your will
вы́нужден ("forced, compelled") is the agreeing-adjective cousin of прихо́дится. It stresses that you act under pressure, reluctantly, with the implication that you would rather not. It is somewhat formal and very common in official or apologetic statements. Forms: вы́нужден / вы́нуждена / вы́нуждены.
Из-за пого́ды мы вы́нуждены отмени́ть рейс.
Because of the weather we are forced to cancel the flight. — formal, stresses unwilling compulsion (plural вы́нуждены).
Она́ была́ вы́нуждена прода́ть кварти́ру.
She was forced to sell the flat. — past: была́ вы́нуждена, agreeing with the feminine subject.
прихо́дится / пришло́сь — forced by circumstance, no choice
This is the expression English speakers most often should be using and almost never are. прихо́дится (imperfective) / пришло́сь (perfective) means "have to / end up having to" because the situation leaves no other option. The person is in the dative; the verb is impersonal and frozen in the neuter/third-person. It is the everyday, neutral way to say "I had no choice but to."
Мне пришло́сь уйти́ ра́ньше — заболе́л ребёнок.
I had to leave early — my child got sick. — пришло́сь: circumstances forced it, not a duty.
Авто́бусов не́ было, и нам пришло́сь идти́ пешко́м.
There were no buses, so we had to walk. — the classic 'no choice' situation.
Прихо́дится рабо́тать по выходны́м, что́бы успе́ть.
I have to work weekends to keep up. — imperfective прихо́дится: a recurring forced situation.
Here is the contrast that the whole page turns on. English "I had to leave" can mean two opposite things, and Russian forces you to pick:
| Russian | Why the obligation exists |
|---|---|
| Мне пришло́сь уйти́. | Circumstances forced me — I had no choice. |
| Я до́лжен был уйти́. | It was my duty / I was supposed to (an expectation, a plan). |
| Мне на́до бы́ло уйти́. | It was practically necessary for me to leave. |
до́лжен — personal duty and expectation
до́лжен ("must / should / am supposed to") is the workhorse of the middle of the spectrum: a personal obligation, a commitment, or an expectation. It is a short adjective with a nominative subject — до́лжен / должна́ / должно́ / должны́ — and is fully covered on its own page. Note its second life: with a dative person and a sum, до́лжен means owe.
Я до́лжен извини́ться пе́ред ней.
I must apologize to her. — moral duty; nominative subject я + agreeing до́лжен.
По́езд до́лжен прийти́ в семь.
The train is supposed to arrive at seven. — до́лжен for an expectation/schedule, not personal duty.
Ты мне до́лжен пятьсо́т рубле́й.
You owe me five hundred rubles. — до́лжен + dative person + sum = 'owe' (no infinitive).
на́до / ну́жно — plain practical necessity
на́до and ну́жно ("need to, it's necessary") sit in the neutral middle: a practical requirement, with no overtone of moral duty or external force. Impersonal, with the person in the dative. ну́жно is marginally more neutral, на́до a shade more colloquial; in speech they are interchangeable. (To need a thing rather than to do something, use the agreeing ну́жен / нужна́ / нужны́ — see должен, надо, нужно.)
Мне на́до зайти́ в апте́ку по доро́ге домо́й.
I need to stop by the pharmacy on the way home. — на́до: an ordinary practical errand, dative мне.
Нам ну́жно реши́ть э́то до пя́тницы.
We need to settle this by Friday. — ну́жно, neutral practical necessity, dative нам.
сле́дует — what is advisable or proper (formal)
сле́дует + infinitive ("one should, it is advisable") is the formal, slightly bookish register's version of "should". You meet it in instructions, official advice, essays, and careful speech, rather than in casual conversation, where на́до does the same job. The person, when named, is in the dative; very often it is left unstated and general. Its past is сле́довало (бы) — "one should have". More on this and сто́ит lives on should, advice: стоит, следовало.
Пе́ред примене́нием сле́дует прочита́ть инстру́кцию.
Before use one should read the instructions. — сле́дует, formal/written advice (a leaflet, a manual).
Вам сле́дует обрати́ться к специали́сту.
You should consult a specialist. — formal, polite advice; dative вам (a doctor or official might say this).
Не сле́довало э́того говори́ть.
That shouldn't have been said. / I shouldn't have said that. — сле́довало (past): a missed proper course of action, with regret.
сто́ит — it's worth doing (the softest)
At the gentle end, сто́ит + infinitive means "it's worth -ing, it would be a good idea to". This is no longer obligation at all — it is a recommendation. Impersonal; the person, if named, is dative. (Don't confuse it with the homonym сто́ит "costs".)
Тебе́ сто́ит посмотре́ть э́тот фильм — о́чень сове́тую.
You should watch this film — I really recommend it. — сто́ит: a friendly recommendation, the softest end of the scale.
Сто́ит ли вообще́ начина́ть э́тот разгово́р?
Is it even worth starting this conversation? — сто́ит ли: 'is it worth...?', weighing whether to act at all.
Past and future across the spectrum
The agreeing family and the impersonal family form their past and future differently — this is where the case split bites hardest.
Agreeing family (до́лжен, обя́зан, вы́нужден) — the быть-verb agrees with the subject:
Она́ должна́ была́ предупреди́ть нас.
She was supposed to warn us. — agreeing past: должна́ была́ (feminine subject).
Мы бу́дем обя́заны верну́ть де́ньги.
We will be obliged to return the money. — agreeing future: бу́дем обя́заны.
Impersonal family (на́до/ну́жно, сле́дует, сто́ит, нельзя́) — a frozen neuter бы́ло / бу́дет, never agreeing:
Мне на́до бы́ло позвони́ть, но я забы́л.
I needed to call but forgot. — frozen neuter бы́ло, even if the speaker is female (never на́до была́).
прихо́дится is its own verb, so it conjugates normally: present прихо́дится, past пришло́сь (neuter, impersonal), future придётся:
Бою́сь, нам придётся подожда́ть.
I'm afraid we'll have to wait. — future of прихо́дится: придётся, with dative нам.
The negatives — three different "don't / must not"
Negating obligation is treacherous because the negatives do not line up neatly with the positives.
| Negative | Meaning | Note |
|---|---|---|
| не на́до / не ну́жно + inf | no need to / don't (bother) | cancels the necessity; also a soft "don't" |
| нельзя́ + inf | must not / may not | prohibition — NOT the negation of на́до |
| не до́лжен + inf | shouldn't / isn't supposed to | often softer than нельзя́ |
The trap: the opposite of на́до ("you need to") is не на́до ("no need / don't"), not нельзя́. нельзя́ is a separate prohibition word meaning "it is forbidden / impossible" — its detail is on можно and нельзя.
Не на́до меня́ провожа́ть, я сам дойду́.
No need to see me off, I'll manage on my own. — не на́до cancels the necessity (and politely declines).
Здесь нельзя́ кури́ть.
You can't smoke here. — нельзя́: a prohibition, not 'no need'.
Ты не до́лжен э́того де́лать.
You shouldn't do that. — не до́лжен: 'ought not', a softer 'don't' than the flat ban нельзя́.
Common Mistakes
❌ Я до́лжен был уйти́, потому́ что не́ было вы́бора.
Off-register — for 'no choice but to leave', Russians say Мне пришло́сь уйти́. До́лжен был implies a duty/plan, not external compulsion.
✅ Мне пришло́сь уйти́, потому́ что не́ было вы́бора.
I had to leave because there was no choice. — пришло́сь for circumstantial force.
❌ Мне обя́зан помо́чь.
Wrong case — обя́зан is an agreeing adjective with a NOMINATIVE subject, not a dative one.
✅ Я обя́зан помо́чь.
I am obliged to help. — nominative я + agreeing обя́зан.
❌ Ей на́до была́ предупреди́ть нас.
Wrong — на́до is impersonal, so the past is frozen neuter бы́ло, never agreeing with 'her'.
✅ Ей на́до бы́ло предупреди́ть нас.
She had to warn us. — dative ей + frozen neuter бы́ло.
❌ Здесь не на́до кури́ть. (meaning 'smoking is forbidden')
Wrong sense — не на́до means 'no need / don't bother', not 'forbidden'. A ban is нельзя́.
✅ Здесь нельзя́ кури́ть.
Smoking is not allowed here. — нельзя́ for prohibition.
❌ Вам сто́ит плати́ть нало́ги. (meaning a legal duty)
Too soft — сто́ит is a friendly recommendation. A legal obligation is обя́заны.
✅ Вы обя́заны плати́ть нало́ги.
You are obliged to pay taxes. — обя́зан for a binding duty.
Key Takeaways
- Russian grades obligation by force and syntax at once. Two families: agreeing short adjectives with a nominative subject (обя́зан, вы́нужден, до́лжен) and impersonal forms with a dative experiencer (нельзя́, прихо́дится, на́до/ну́жно, сле́дует, сто́ит).
- обя́зан = binding/formal duty (stronger than до́лжен); вы́нужден = compelled, reluctant; до́лжен = personal duty or expectation; на́до/ну́жно = plain practical need; сле́дует = advisable (formal); сто́ит = worth doing (softest).
- прихо́дится / пришло́сь (dative) is the everyday way to say "had to with no choice" — choose it over до́лжен был when circumstances, not duty, force the action: Мне пришло́сь уйти́.
- Past/future: the agreeing family takes an agreeing быть (должна́ была́, бу́дем обя́заны); the impersonal family takes a frozen neuter бы́ло / бу́дет (Ей на́до бы́ло). прихо́дится conjugates as its own verb (пришло́сь, придётся).
- The negatives don't mirror the positives: не на́до = "no need / don't", while нельзя́ = "must not". Don't substitute one for the other.
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- Must and Need: Должен, Надо, НужноA2 — Russian splits 'must / need' across two grammatically opposite patterns. До́лжен/должна́/должно́/должны́ is a short adjective agreeing with a NOMINATIVE subject (Я до́лжен идти́, Она́ должна́ рабо́тать). На́до / ну́жно are impersonal with the person in the DATIVE (Мне на́до идти́). And ну́жен/нужна́/ну́жно/нужны́ flips again to agree with the needed THING (Мне нужна́ кни́га, Ему́ нужны́ де́ньги). Includes past/future (Я до́лжен был, Мне на́до бы́ло).
- Permission and Prohibition: Можно, НельзяA2 — Two impersonal words handle 'may' and 'may not'. Мо́жно = it's allowed / it's possible (Здесь мо́жно кури́ть? Мне мо́жно войти́? Мо́жно вопро́с?). Нельзя́ is its negative — and its meaning splits by ASPECT: нельзя́ + imperfective = prohibition ('mustn't': Здесь нельзя́ кури́ть), нельзя́ + perfective = impossibility ('can't manage to': Дверь нельзя́ откры́ть). The same word means 'forbidden' or 'impossible' depending purely on the infinitive's aspect — a distinction almost no course teaches.
- Giving Advice: стоит, следует, лучше быB2 — English 'should' for ADVICE (not obligation) is rendered in Russian with сто́ит + infinitive ('it's worth / you should': Тебе́ сто́ит отдохну́ть), лу́чше + infinitive ('better to'), or the formal сле́дует / сле́довало бы. The dative names the person advised, and Не сто́ит is the standard soft 'you shouldn't / no point'. This page orders the advice constructions by register and strength, contrasts them with the stronger до́лжен / на́до, and shows how бы softens any of them.
- Expressing 'Have To' and 'Need To': A SummaryA2 — A compact A2 cheat-sheet of the high-frequency ways to say must / need / it's time in Russian. До́лжен agrees with a nominative subject; на́до/ну́жно are impersonal with a dative experiencer; ну́жен agrees with the needed thing; пора́ means 'it's time'. One comparison table, plus past and future.
- Dative with Impersonal Modals (можно, нужно, нельзя, пора)A2 — Russian expresses most modality about people with a frozen pattern: dative person + impersonal word + infinitive. Мне на́до идти́ (I have to go), Вам мо́жно войти́ (you may come in), Ему́ нельзя́ кури́ть (he mustn't smoke), Нам пора́ е́хать (it's time for us to go), Тебе́ тру́дно поня́ть (it's hard for you to understand). Past/future insert frozen neuter бы́ло/бу́дет (Мне на́до бы́ло уйти́). The experiencer is the DATIVE — there's no nominative 'I'. Plus the agreeing ну́жен/нужна́/ну́жно/нужны́ for needing a thing (Мне нужна́ по́мощь, Мне нужны́ де́ньги).
- Dative Subjects: Feelings, Age, NecessityA2 — In a signature Russian construction the logical subject — the person experiencing a state — stands in the DATIVE, not the nominative, and there is often no nominative subject and no real verb at all. Feelings: Мне хо́лодно (I'm cold), Ему́ ску́чно (he's bored). Age: Мне два́дцать лет (I'm 20). Necessity/permission: Мне на́до идти́ (I have to go), Здесь нельзя́ кури́ть (you can't smoke here). Liking: Мне нра́вится му́зыка (music is pleasing to me — the liked thing is the nominative subject!). The verb, when present, is frozen neuter. This is where English speakers most resist Russian, and mastering it is the gateway to sounding native.