Comparisons with jako by / jako kdyby

To say "as if" or "as though" in Czech — Tváří se, jako by nic nevěděl ("He acts as if he knew nothing") — you reach for jako by or jako kdyby plus the conditional. The English "as if" is a clue that what follows is not real: the person doesn't actually know nothing, they just behave that way. Czech makes this unreality explicit by forcing the conditional, the same mood it uses for everything hypothetical. This page shows how the construction is built, how the auxiliary agrees in person, and how to get the past-unreal reading.

This builds directly on the present conditional and on kdyby clauses; if those are shaky, start there.

The core idea: an unreal comparison

jako by introduces a comparison with a hypothetical situation — you describe how something looks, sounds, or feels by likening it to a scenario that isn't actually the case. Because the scenario is counterfactual, Czech requires the conditional, exactly as it does in kdyby ("if") clauses. In fact kdyby is itself když + by, and jako kdyby is "as-when-would": "as it would be when…".

The first clause states what you actually observe (Vypadá — "he looks"); jako by then supplies the imagined situation that the appearance resembles.

The auxiliary is built into jako by — and it agrees in person

This is the point English speakers miss. by is the third-person conditional auxiliary, but when the implied subject of the comparison is "I," "you," or "we," the auxiliary changes form and fuses into the jako phrase. You don't add a separate bych elsewhere — it lives right there after jako:

So "I felt as if I were flying" uses jako bych, agreeing with the implied "I":

The same kdyby variant agrees identically: jako kdybych, jako kdybys, jako kdyby, jako kdybychom, jako kdybyste, jako kdyby. The two are interchangeable in meaning; jako kdyby is a touch more emphatic and very common in speech.

jako by vs jako kdyby — is there a difference?

In practice, very little. Both mean "as if / as though" and both take the conditional. jako kdyby is marginally more frequent in everyday speech and feels slightly more vivid; jako by is a hair more compact and common in writing. Pick either — native speakers switch freely.

The past-unreal reading

Czech does not have a separate "as if he had done" form sitting ready-made the way English does. The present conditional inside jako by already covers both "as if he were (now)" and, from context, "as if he had been." The time reference comes from the main clause and the situation, not from a tense change inside the comparison:

When you genuinely need to force a clear past-unreal ("as if it had already happened before then"), you can deploy the full past conditional — byl by + l-participle — inside the comparison, but this is heavy and largely (literary):

For most purposes, the simple jako by + l-participle above is what you want. The plain past conditional itself is covered on the past conditional page.

Why "as if" cannot take the indicative

English allows a sloppy "He acts like he knows everything" with a plain present. Czech does not: the comparison is to an unreal situation, so the conditional is obligatory. Using the indicative (jako že ví) either sounds broken or flips the meaning into "the fact that he knows," which is not a comparison at all.

This is the single most important takeaway: as if = jako by/kdyby + conditional, never jako + indicative.

Common mistakes

Key takeaways

• "As if / as though" = jako by or jako kdyby
  • the conditional (an unreal comparison).
• The conditional auxiliary is fused into the phrase and agrees in person: jako bych, jako bys, jako by, jako bychom, jako byste, jako by.
• The verb of the comparison appears as the l-participle: jako by spal, jako bych letěl.
• The same form covers "as if (now)" and "as if (had)"; the past reading comes from context.
• Never use the bare indicative after jako for a comparison — that is the textbook error.