Forming the Conditional | Czech Grammar

The Czech conditional is what you reach for to say would, 'd like, and a polite could you. The good news for the learner is that it is mechanically simple: it is built from a form you already know — the l-participle (the same one the past tense uses) — plus a small, fixed set of auxiliary words: bych, bys, by, bychom, byste, by. There is no separate "conditional conjugation" to memorize verb by verb. Learn these six little words once, and you can put any Czech verb into the conditional.

The formula

conditional = l-participle (agrees in gender and number) + conditional auxiliary (agrees in person)

The l-participle carries the lexical meaning and agrees with the subject in gender and number (the same -l / -la / -lo / -li / -ly / -la endings you use in the past — see the l-participle). The auxiliary carries the person. So the two halves divide the work: the participle says which verb and what gender, the auxiliary says who.

Dělal bych to jinak.

I would do it differently (said by a man).

Dělala bych to jinak.

I would do it differently (said by a woman).

Notice that bych did not change — only the participle swapped -l for -la to match a female speaker. The auxiliary tracks person, never gender.

The conditional auxiliary

These six forms are unique to the conditional — they are not the verb být "to be." Learn them as a unit.

Person	Auxiliary
já (I)	bych
ty (you sg.)	bys
on / ona / ono (he/she/it)	by
my (we)	bychom
vy (you pl./formal)	byste
oni (they)	by

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The 2nd-person singular bys is a single fused word standing for "by + jsi." In casual speech you will hear it broken up into by jsi (or even by si), but that is non-standard — in writing and careful speech, always bys. The same goes inside the fused conjunctions: kdybys, not kdyby jsi; abys, not aby jsi.

Present conditional of dělat "to do, make"

Putting the two halves together, here is the full present conditional, shown with a masculine subject in the singular. Swap -l → -la for a female subject, -lo for neuter.

Person	Conditional	Meaning
já	dělal bych	I would do
ty	dělal bys	you would do
on / ona / ono	dělal / dělala / dělalo by	he / she / it would do
my	dělali bychom	we would do
vy	dělali byste	you (pl./formal) would do
oni	dělali by	they would do

In the plural the participle takes the usual animacy-sensitive endings: dělali (masculine animate), dělaly (feminine / masculine inanimate), and dělala for the neuter plural.

What the conditional does

Three everyday jobs cover almost all of A2-level use:

1. Hypothetical "would." The action is imagined, not asserted.

Co bys dělal na mém místě?

What would you do in my place?

Nejradši bych zůstala doma.

I'd most like to stay home (said by a woman).

2. Polite "I'd like / could you." This is the workhorse of everyday courtesy — softening a request into something less blunt than the bare present. Chci "I want" becomes the gentler chtěl bych "I would like"; můžete "you can" becomes mohl byste "could you."

Chtěl bych kávu a sklenici vody, prosím.

I'd like a coffee and a glass of water, please (said by a man).

Mohl byste mi prosím pomoct s tím kufrem?

Could you please help me with this suitcase? (formal)

3. Mild "should / ought to," built on mít "to have" in the conditional (měl bych).

Neměl bys tolik pracovat.

You shouldn't work so much.

The auxiliary is a second-position clitic

Here is the one piece of word order you must respect. bych, bys, by… are clitics — unstressed little words that have to sit in second position in the clause, right after the first stressed unit. They cannot open a sentence, and they cling close to the front, not next to their verb.

Rád bych ti pomohl.

I'd be glad to help you (said by a man).

Na tvém místě bych to neudělal.

In your place I wouldn't do it (said by a man).

In Na tvém místě bych to neudělal, the auxiliary bych comes right after the opening phrase na tvém místě — long before the participle neudělal at the very end. This is the same second-position rule that governs the past-tense jsem and object pronouns; for the full picture see clitics in second position.

Fused conjunctions: kdyby and aby

Two extremely common conjunctions swallow the conditional auxiliary and conjugate for person themselves. You must never separate them.

kdyby = "if" (hypothetical) — the conjunction that introduces an irreal condition.
aby = "so that, in order to" — the conjunction of purpose.

Each one fuses the auxiliary into a single conjugated word:

Person	"if" (kdyby)	"so that" (aby)
já	kdybych	abych
ty	kdybys	abys
on/ona/ono	kdyby	aby
my	kdybychom	abychom
vy	kdybyste	abyste
oni	kdyby	aby

The practical upshot: you can never say když bych or aby bych. The "if" already carries its person ending — kdybych měl "if I had," kdybys měl "if you had."

Kdybych měl víc času, naučil bych se hrát na kytaru.

If I had more time, I'd learn to play the guitar (said by a man).

Zavolej mi, abych věděl, že jsi v pořádku.

Call me so that I know you're okay (speaker is male: věděl).

For how these two conjunctions build whole subordinate clauses, see aby and kdyby clauses.

The past (irreal) conditional: byl bych dělal

To talk about something that would have happened but didn't — a counterfactual about the past — Czech has a past conditional. It adds the l-participle of být (byl / byla / bylo / byli…) on top of the present conditional structure:

past conditional = byl/byla… + bych/bys… + main l-participle

Byl bych ti zavolal, ale ztratil jsem telefon.

I would have called you, but I lost my phone (said by a man).

Kdybys mi to řekla dřív, byli bychom přijeli včas.

If you'd told me sooner, we would have arrived on time (said to a woman).

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The past conditional is increasingly (formal/literary). In ordinary modern speech, most Czechs use the present conditional even for counterfactual past events and let context supply the "would have": Kdybys mi to řekla dřív, přijeli bychom včas is what you will far more often hear. Recognize byl bych přišel, but don't feel obliged to produce it in casual conversation.

Reflexive verbs in the conditional

When the verb is reflexive, its se or si joins the clitic cluster right after the auxiliary. In the 2nd-person singular the two fuse: bys + se → by ses, bys + si → by sis.

Měl by sis odpočinout.

You ought to get some rest (said to a man; sis = bys + si).

Nebál by ses tam jít sám?

Wouldn't you be afraid to go there alone? (ses = bys + se)

Common Mistakes

❌ Když bych měl čas, přišel bych.

Incorrect — 'if' + conditional fuses to kdyby; you can never say *když bych.

✅ Kdybych měl čas, přišel bych.

If I had time, I would come.

❌ Bych chtěl kávu.

Incorrect — the auxiliary is a clitic and cannot open the sentence.

✅ Chtěl bych kávu.

I'd like a coffee.

❌ Ty by jsi to nedělal.

Non-standard — 'by + jsi' should be the single form bys.

✅ Ty bys to nedělal.

You wouldn't do it.

❌ My by jsme šli.

Incorrect — the 1st-plural auxiliary is bychom, not *by jsme.

✅ My bychom šli.

We would go.

❌ Mohl by jste mi pomoct?

Incorrect — the formal/plural auxiliary is byste, written as one word.

✅ Mohl byste mi pomoct?

Could you help me? (formal)

Key Takeaways

Conditional = l-participle (gender/number) + auxiliary (person): dělal bych, dělala bys, dělali bychom.
The six auxiliary forms — bych, bys, by, bychom, byste, by — are fixed and are not the verb být.
The auxiliary is a second-position clitic: it can't start the clause and clings to the front, away from the participle.
"If" and "so that" fuse the auxiliary: kdyby → kdybych…, aby → abych…; never když bych or aby bych.
The past conditional (byl bych přišel) exists but is now mostly formal/literary; the present conditional covers most counterfactual past in speech.
2nd singular is bys (standard), not by jsi; with reflexives it fuses to by ses / by sis.

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