English has one future machine — "will" plus a verb — and uses it for everything. Czech has two, and which one you use is not your choice: it is decided entirely by the aspect of the verb. Imperfective verbs build the future with budu + the infinitive (budu psát — "I'll be writing"). Perfective verbs have no budu-future at all; their ordinary present-tense form already means the future (napíšu — "I'll write it"). Once you see that aspect drives the whole thing, the future tense stops being two competing patterns and becomes a single yes/no question.
The one rule
Is the verb perfective? Then use its present-tense form — that is its future (napíšu, koupím, přijdu). Is the verb imperfective? Then use budu / budeš / bude … + the infinitive (budu psát, budeš kupovat, bude čekat).
That's the whole decision. There is no third option, and crucially the two patterns never mix: you never put budu in front of a perfective.
The imperfective future: budu + infinitive
Conjugate být into its special future stem and add the imperfective infinitive. This future emphasizes the process — something ongoing, repeated, or happening over a stretch of time.
| Subject | budu + infinitive (e.g. psát) |
|---|---|
| já | budu psát |
| ty | budeš psát |
| on / ona / ono | bude psát |
| my | budeme psát |
| vy | budete psát |
| oni | budou psát |
Zítra budu celý den pracovat na zahradě.
Tomorrow I'll be working in the garden all day.
Budeme se učit česky každý večer.
We'll study Czech every evening.
Bude na tebe čekat před kinem.
He'll be waiting for you in front of the cinema.
All three verbs (pracovat, učit se, čekat) are imperfective, and the meaning is durative or habitual: an activity filling a span, a recurring routine, an ongoing wait. That is exactly what the budu-future is for.
The perfective future: the present form does the job
A perfective verb has no separate future construction. Because a perfective names a single completed event — and a completion cannot be happening "now" — its present-tense endings are pushed forward to mean the future automatically. So napíšu is built like a present but means "I'll write (and finish) it."
Napíšu ten e-mail hned po obědě.
I'll write that email right after lunch.
Koupím chleba cestou domů.
I'll buy bread on the way home.
Přijdu v pět, slibuju.
I'll come at five, I promise.
Udělám to dnes večer, neboj.
I'll do it tonight, don't worry.
Napíšu, koupím, přijdu, udělám are all perfective verbs in present-tense endings, every one pointing to a single future result. There is no budu anywhere — and there must not be.
The contrast, paired
The clearest way to feel the split is to take an aspect pair and put both futures side by side. Same root, same rough meaning, different aspect, different machinery:
Budu se učit celé odpoledne.
I'll be studying all afternoon. (imperfective — the process)
Naučím se to do zítřka.
I'll learn it by tomorrow. (perfective — the result)
The first describes the activity of studying over a span; the second promises the achieved outcome of having learned it. Budu se učit uses budu + infinitive because učit se is imperfective; naučím se is just the present form of perfective naučit se, already future.
Budu psát ten článek celý víkend.
I'll be writing that article all weekend. (process)
Napíšu ten článek do pondělí.
I'll write that article by Monday. (completion)
Notice the time expressions tracking the aspect: celý víkend ("all weekend," a span) pairs with the imperfective process; do pondělí ("by Monday," a deadline for completion) pairs with the perfective result.
The cardinal error: *budu + perfective
The single most important thing to never do is combine budu with a perfective infinitive. It is the textbook beginner mistake, and it is flatly ungrammatical. Budu is reserved for imperfective infinitives; the perfective already carries its own future, so adding budu is like saying "I will will-do." There is no such form as *budu napsat or *budu se naučit.
Naučím se to do víkendu.
I'll learn it by the weekend. (correct perfective future)
The reason this trap is so seductive for English speakers is that English really does use one pattern — "I will study" and "I will learn" look identical. The aspect distinction that splits them in Czech is invisible in English, so learners reach for budu every time, including where it's forbidden.
A quick flowchart
Run this every time you build a future:
- What does the verb mean — a single completed result, or an ongoing / repeated / process action? That tells you the aspect to pick (perfective for the result, imperfective for the process).
- Is the verb I've chosen perfective? → Use its present-tense form. Done. (napíšu, koupím, přijdu)
- Is it imperfective? → Use budu
- the infinitive. Done. (budu psát, budu kupovat, budu přicházet)
- Never put budu in front of a perfective infinitive.
The motion-verb exception you should know
The basic motion verbs jít ("go on foot") and jet ("go by vehicle") form their future irregularly, with the prefix po-, not with budu: půjdu ("I'll go on foot") and pojedu ("I'll go/drive"). These behave like perfectives in that they're single words pointing to the future, so they fit the "no budu" side of the rule.
Zítra půjdu pěšky do práce.
Tomorrow I'll walk to work.
V létě pojedeme k moři.
In summer we'll drive to the seaside.
You'll never say *budu jít or *budu jet for these; see the motion futures půjdu / pojedu for the full picture.
Common Mistakes
❌ Budu napsat ten dopis večer.
Incorrect — budu cannot take a perfective infinitive; the perfective present already means the future.
✅ Napíšu ten dopis večer.
I'll write that letter in the evening.
❌ Budu se naučit česky.
Incorrect — naučit se is perfective, so no budu; use its present form.
✅ Naučím se česky.
I'll learn Czech.
❌ Koupit budu nové boty zítra.
Incorrect — perfective koupit has no budu-future; just use koupím.
✅ Koupím si zítra nové boty.
I'll buy new shoes tomorrow.
❌ Zítra napíšu na tom projektu celý den.
Incorrect — a whole day of working on something is a process, which needs the imperfective budu-future.
✅ Zítra budu celý den pracovat na tom projektu.
Tomorrow I'll work on that project all day.
❌ Budu jít do kina v sobotu.
Incorrect — jít forms its future irregularly as půjdu, not with budu.
✅ Půjdu do kina v sobotu.
I'll go to the cinema on Saturday.
Key Takeaways
- The future form is dictated by aspect, not by you: perfective → present-as-future; imperfective → budu
- infinitive.
- Perfective verbs (napíšu, koupím, přijdu, udělám) have no budu-future — their present form is the future.
- Imperfective verbs (budu psát, budu se učit, budu čekat) use budu
- infinitive for ongoing, repeated, or process actions.
- *budu
- perfective is always wrong — the trap English speakers fall into by treating all verbs like "will + verb."
- Motion jít/jet make irregular futures půjdu/pojedu with no budu.
- See aspect in the future for the deeper account and aspect in the present for why the perfective present means the future.
Now practice Czech
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Start learning Czech→Related Topics
- The Imperfective Future (budu + infinitive)A2 — How Czech builds the future of imperfective verbs with budu + an infinitive, why it pairs only with imperfectives, and when to use it instead of the perfective.
- The Perfective Future (= perfective present)B1 — How the perfective present form expresses a completed future action.
- Choosing the Right FutureB1 — A decision guide for imperfective vs perfective future and motion futures.
- Special Motion Futures (půjdu, pojedu)B1 — The irregular prefixed futures of jít and jet.
- Aspect in the Future TenseB1 — The two Czech futures, which aspect each one uses, and why budu + perfective is impossible.
- Aspect in the Present TenseB1 — Why only imperfectives have a true present and what perfective 'present' means.