Bugün bütün gün evde kalıyorum.

They do, but they answer different time questions:

• bugün = today → which day?
• bütün gün = all day / the whole day → for how long?

So together they mean something like:

• Today, I’m staying home all day.

Using both is very natural because one gives the day, and the other gives the duration.

bütün means whole / entire / all and gün means day.

So bütün gün literally means the whole day or all day.

It is a very common expression in Turkish:

• bütün gece = all night
• bütün hafta = all week

Ev means house / home.
The ending -de is the locative suffix, which means in / at / on depending on context.

So:

• ev = home, house
• evde = at home / in the house

The suffix appears as -de here because of vowel harmony and consonant harmony. After ev, -de is the correct form.

Kalıyorum comes from the verb kalmak, which often means to stay / remain.

Breakdown:

• kal- = verb stem
• -ıyor = present continuous suffix
• -um = I

So kalıyorum means:

• I am staying
• I stay (in some contexts)
• sometimes even I’m going to stay, depending on context

In this sentence, it means I’m staying home.

In Turkish, the present continuous form is used much more broadly than English am/is/are + -ing.

So kalıyorum can mean:

• I am staying
• I’m staying today
• I’ll be staying
• I stay

With time words like bugün, Turkish often uses the present continuous for what English might express as a present plan or a current situation.

So Bugün bütün gün evde kalıyorum is perfectly natural for:

• I’m staying home all day today.

Yes. That is very common in Turkish.

The -iyor form can describe:

• something happening right now
• something already decided or planned
• a temporary situation

So this sentence could mean:

• I’m at home all day today
• I’m staying home all day today
• I’ll be staying home all day today

The exact nuance depends on context.

Turkish often leaves out subject pronouns because the verb ending already shows the subject.

In kalıyorum, the ending -um tells us the subject is I.

So:

• (Ben) bugün bütün gün evde kalıyorum.
• Bugün bütün gün evde kalıyorum.

Both are correct.
Usually ben is omitted unless you want emphasis, contrast, or clarity.

For example:

• Ben bugün bütün gün evde kalıyorum, sen dışarı çıkıyorsun.
  • I’m staying home all day today, but you’re going out.

Yes, Turkish word order is flexible, but the neutral order here is very natural:

• Bugün = today
• bütün gün = all day
• evde = at home
• kalıyorum = I’m staying

The verb usually comes at the end.

You can rearrange parts for emphasis, for example:

• Evde bütün gün bugün kalıyorum would sound unusual in many contexts.
• Bugün evde bütün gün kalıyorum is possible.
• Bütün gün evde kalıyorum bugün is also possible in speech for emphasis.

But the most natural neutral version is:

• Bugün bütün gün evde kalıyorum.

Because kalmak is the normal verb for staying somewhere.

• evde kalmak = to stay at home
• oturmak usually means to sit or sometimes to live/reside
• durmak usually means to stop or to stand/remain still

So:

• evde kalıyorum = I’m staying at home is the most natural choice here.

If you said evde oturuyorum, it could mean:

• I am sitting at home, or in some contexts
• I live at home

That is not the same idea.

This is a very common and important distinction:

• evde = at home / in the house → location
• eve = to home / to the house → direction

So:

• Evde kalıyorum. = I’m staying at home.
• Eve gidiyorum. = I’m going home.

In your sentence, the idea is location, so evde is correct.

Yes, in many contexts bütün and tüm both mean all / whole.

So:

• Bugün bütün gün evde kalıyorum.
• Bugün tüm gün evde kalıyorum.

Both are understandable.

However, bütün gün is very common and often feels a bit more natural in everyday speech.

Usually evde is best understood as at home.

Literally, it comes from ev = house/home, so it can also mean in the house, but in ordinary use it often functions like English at home.

So the sentence naturally means:

• I’m staying at home all day today.

You add the negative marker to the verb:

• Bugün bütün gün evde kalmıyorum.

This means:

• I’m not staying home all day today.

Breakdown:

• kal- = stay
• -mıyor = not staying
• -um = I

So kalıyorum → kalmıyorum.

You add the question particle mu/mü/mı/mi separately, following vowel harmony:

• Bugün bütün gün evde kalıyor muyum?
  • Am I staying home all day today?

More commonly in direct conversation, you might ask someone else:

• Bugün bütün gün evde kalıyor musun?
  • Are you staying home all day today?

Notice that the question particle is written separately:

• kalıyor muyum
• kalıyor musun

Yes, it is completely natural.

A native speaker would understand it as something like:

• I’m staying home all day today.

It sounds like normal spoken or written Turkish, especially when talking about plans, availability, or what you are doing today.