měl by + Infinitive

Recommendation with Měl by

Level 5

The pattern měl by + infinitive is the standard way to say "should" or "ought to" in Czech. It expresses personal advice, a mild obligation, or a strong expectation.

How It Works

This pattern is highly versatile and register-neutral. It is used for three main purposes:

1. Advice and Mild Obligation: Giving recommendations based on personal opinion (e.g., Měl bys jít k doktorovi. - You should go to the doctor).
2. Epistemic Expectation: Stating that something is highly likely or expected to happen based on normal circumstances (e.g., Ten balík by už měl dorazit. - The package should arrive by now).
3. Hearsay / Reported Information: Stating what is scheduled or rumored to happen (e.g., Prezident by měl zítra dorazit do Prahy. - The president is supposed to arrive in Prague tomorrow).

Crucial Grammar Rules:

  • Agreement: The word měl is an l-participle and must agree with the subject in gender and number (e.g., měl bys to a male, měla bys to a female, mělo by for neuter, and měli / měly / měla byste for plural depending on gender). For formal singular address (vykání), the participle agrees with the natural gender of the person: měl byste (to a man) or měla byste (to a woman).
  • Auxiliary Forms & Placement: The conditional auxiliary (bych, bys, by, bychom, byste, by) generally occupies the second position in main clauses. However, in subordinate clauses, it fuses with conjunctions like když and aby (forming kdybych, abych, etc.) and occupies the first position. Note that the third-person plural auxiliary remains by (e.g., měli by - they should). In colloquial spoken Czech, the first-person plural bychom is often replaced by the non-standard bysme.
  • Negation: The negative prefix ne- attaches to the l-participle, not the auxiliary (e.g., neměl bys - you shouldn't).
  • Reflexive Fusion: In the second-person singular, bys fuses with reflexive pronouns to form by ses and by sis. Note that these are explicitly written as two separate words. The conditional auxiliary must come first in the clitic cluster, immediately followed by the reflexive pronoun (e.g., Měl by sis to přečíst. - You should read it).
  • Time Reference: Despite using the past participle měl, this pattern refers to the present or future. To explicitly say "should have" (past regret), modern Czech typically uses the past tense of mít + infinitive (e.g., Měl jsi to udělat. - You should have done it). Alternatively, the past conditional (e.g., Byl bys to měl udělat.) can be used as an archaic or highly formal equivalent.

Contrasts:
Do not confuse this with the present tense of mít (mám, máš + infinitive), which implies an external schedule or instruction ("is supposed to"), or with muset (musí), which is a hard obligation ("must").

Examples (5)

  1. Měl bys jít k doktorovi, ten kašel zní hrozně.

    You should go to the doctor, that cough sounds awful.

    Word by Word: Should would-you go to doctor, that cough sounds terribly.

    Used to give personal advice or a strong recommendation.

  2. Ten balík by už měl dorazit.

    The package should have arrived by now.

    Word by Word: That package would already should arrive.

    Used for epistemic expectation—stating what is likely to happen based on normal circumstances.

  3. Neměli bychom na to čekat do poslední chvíle.

    We shouldn't wait for it until the last minute.

    Word by Word: Not-should would-we for it wait until last minute.

    The negative form expresses what is inadvisable. Notice the auxiliary 'bychom' follows the first element 'Neměli'.

  4. Zítra bych měla jít do práce, ale necítím se dobře.

    I should go to work tomorrow, but I don't feel well.

    Word by Word: Tomorrow would-I should go to work, but not-feel myself well.

    Shows a female speaker (měla). The clitic 'bych' takes the strict second position, separating from 'měla'.

  5. Měl by ses víc učit.

    You should study more.

    Word by Word: Should would-you-yourself more study.

    Demonstrates the mandatory fusion of the auxiliary 'bys' and the reflexive pronoun 'se' into 'by ses'.

Common Mistakes

  • Omitting the past participle 'měl' and using only the conditional auxiliary.

    Já bych jít domů.
    Měl bych jít domů.

    English speakers often try to translate "should" using only the conditional particle and the infinitive. You must include the past participle of 'mít' (měl/měla/mělo...).

  • Splitting the second-person clitic, failing to fuse it with reflexives, or writing 'by jste'.

    Měl by jsi se víc učit.
    Měl by ses víc učit.

    In standard Czech, the auxiliary 'bys' fuses with the reflexive pronoun 'se' to form 'by ses' (and with 'si' to form 'by sis'). Writing 'by jsi' is non-standard. Similarly, you will often see native speakers incorrectly write 'by jste' instead of the correct standard form 'byste'.

  • Placing the conditional clitic in the wrong position.

    Zítra měl bych jít do banky.
    Zítra bych měl jít do banky.

    The conditional auxiliary (bych, bys, by, bychom, byste, by) is a Wackernagel clitic and must strictly occupy the second syntactic position in the clause, right after the first element ('Zítra').

How It Connects

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měl by + InfinitiveLevel 5Recommendation with Měl by

Learn This First

To understand 'měl by + infinitiv', a learner needs to be familiar with the verb 'mít' and how the Czech conditional mood is constructed using the past participle (měl) combined with the conditional auxiliary (by, bych, bys, etc.).

Words in This Pattern

mítby