Learn Hardcore Czech: Mám nový kalendář a plánuji v něm celý týden. - I have a new calendar and I plan my whole week in it.

Gender
- kalendář is masculine inanimate (like hrad type nouns).
- The adjective nový must agree with it in gender, number, and case → nový kalendář.
Case (Accusative)
- The verb mít (to have) takes its object in the accusative case.
- Masculine inanimate accusative = same as nominative:
  - nominative: nový kalendář
  - accusative: nový kalendář
If it were masculine animate, you often see a change:
- nominative: nový učitel (new teacher)
- accusative: nového učitele

Here it stays nový kalendář because it’s masculine inanimate in the accusative.

Why is there no word like “a” or “the” before nový kalendář in Czech?

Czech has no articles (no equivalents of a/an/the as separate words).
Definiteness is understood from context, word order, stress, or extra words if needed (like ten = that/the).

So:

Mám nový kalendář.
Can mean: I have a new calendar or I have the new calendar, depending on context.

If you really need to stress “that specific calendar,” you might say:

Mám ten nový kalendář. = I have that new calendar / the new calendar (we talked about).

What’s the difference between plánuji and plánuju? Which should I use?

Both plánuji and plánuju are correct 1st person singular present of plánovat (to plan).

plánuji – more formal / standard / written
plánuju – more colloquial / spoken / everyday

In your sentence:

Mám nový kalendář a plánuji v něm celý týden. – perfectly standard, good for writing.
Mám nový kalendář a plánuju v něm celý týden. – sounds more conversational.

As a learner, it’s safest to learn both: recognize both, mostly use plánuji in writing, and plánuju in casual speech.

What exactly does v něm mean, and why that form?

v něm literally = “in it”.

v = preposition “in”
něm = form of the pronoun on (he/it) in the locative case

Why locative?

The preposition v (“in, inside”) normally requires the locative case when it expresses location.
We’re talking about where the planning happens (inside the calendar), so v + locative.

kalendář (masc. inanimate) in locative is:

(o) kalendáři = about/in the calendar

The pronoun on in locative singular is:

v něm = in it (referring to the calendar)

So v něm replaces v kalendáři to avoid repetition:

Mám nový kalendář a plánuji v kalendáři celý týden.
Mám nový kalendář a plánuji v něm celý týden. ✅

Why is it něm and not něj in v něm?

Both něm and něj are forms of the 3rd person masculine pronoun (on), but they are different cases:

něm = locative (used after v, na, o, etc. when they require locative)
něj = normally accusative (or sometimes genitive after certain prepositions)

Since v here expresses location (in something) and wants the locative, we must use něm:

v něm = in it (locative) ✅
na něj = onto him/it (motion, accusative)
bez něj = without him/it (genitive)

So for v + location, think: v + něm, not v + něj.

Why is there no “I” (já) in the Czech sentence?

Czech is a “pro-drop” language: the subject pronoun is often omitted because the verb ending already shows who the subject is.

mám = I have
plánuji = I plan

So:

Já mám nový kalendář a já plánuji v něm celý týden. – grammatically OK, but sounds heavy / overly emphatic.
Mám nový kalendář a plánuji v něm celý týden. – natural, neutral.

You use já mainly for contrast or emphasis:

Já mám nový kalendář, ale on ho nemá.
I have a new calendar, but he doesn’t.

Why is celý týden in that form? What case is it?

celý týden is in the accusative case. Two main interpretations are possible, and both use the accusative:

Object of the verb:
- plánuji (co?) celý týden
- I plan (what?) the whole week – i.e. I plan out all the days of the week.
Duration of time:
- Czech often uses accusative to express “for how long”:
- Byl tam celý týden. = He was there (for) the whole week.

In your particular sentence, context usually suggests meaning 1 (planning the whole week in the calendar), but grammatically both readings are possible, and the form celý týden (accusative) fits both.

Forms:

nominative: celý týden
accusative: celý týden (same form for masculine inanimate)

Could the word order be different, like Plánuji v něm celý týden or Plánuji celý týden v něm?

Yes, Czech word order is fairly flexible, and all of these are possible:

Mám nový kalendář a plánuji v něm celý týden.
– Neutral: I have a new calendar and (I) plan the whole week in it.
Mám nový kalendář a plánuji celý týden v něm.
– Slight emphasis on “v něm” (in it) – not somewhere else.
Mám nový kalendář a v něm plánuji celý týden.
– Emphasis on “v něm” at the beginning of the second clause.
Mám nový kalendář a celý týden plánuji v něm.
– Emphasis on celý týden (the whole week).

Meaning doesn’t radically change, but focus and emphasis do.
The original word order is very natural and neutral.

Is celý týden here “the whole week (as an object)” or “all week long (duration)”?

It can be understood both ways, and context decides:

“The whole week” as what is being planned (object):
- I have a new calendar and I plan the whole week in it (I schedule all the days).
“All week long” as duration of the activity:
- I have a new calendar and I spend the whole week planning in it.

Without more context, Czech listeners will most naturally understand it as planning out the whole week (option 1), because that fits what we typically do in a calendar.
Grammatically, however, both readings use accusative and both are correct.

Could I say Mám nový kalendář a plánuji si v něm celý týden? What does si do?

Yes, you can say:

Mám nový kalendář a plánuji si v něm celý týden.

The little word si is a reflexive dative pronoun; here it roughly adds the idea “for myself” or “for my own benefit”.

plánuji v něm celý týden – neutral: I plan the whole week in it.
plánuji si v něm celý týden – I plan the whole week in it for myself (more personal, colloquial, very common in speech).

It doesn’t change the core meaning much, but it sounds more natural and “everyday Czech.” Many verbs in Czech commonly take si in this way: kupovat si, psát si, číst si, dělat si plány, etc.

Does kalendář mean only a paper calendar, or could it also be, for example, a phone calendar?

kalendář can refer to any type of calendar:

a wall calendar
a desk calendar
a paper planner/diary
a digital/phone calendar (Google Calendar, Outlook, etc.)

Whether it’s physical or digital is understood from context or can be specified:

Mám nový papírový kalendář… – a new paper calendar
Mám nový kalendář v mobilu… – a new calendar app / setup on my phone

So your sentence is compatible with both; it just means you have a new calendar system and you’re using it to plan your week.