Ich habe heute Pech.

Because German expresses this idea with the noun Pech and the verb haben: Pech haben = to have bad luck / to be unlucky.

So German says:

• Ich habe Pech. = I have bad luck.
• More natural English meaning: I’m unlucky.

Using sein here would not be idiomatic.

In this sentence, Pech means bad luck.

It is also a regular German noun with another literal meaning: pitch / tar. But in everyday speech, Pech haben is a very common expression meaning to be unlucky.

Examples:

• Heute habe ich Pech. = I’m unlucky today.
• Er hat immer Pech. = He always has bad luck.

Because in the expression Pech haben, Pech is normally used without an article.

So you say:

• Ich habe Pech.

not usually:

• Ich habe das Pech.

In this meaning, Pech behaves a bit like an uncountable noun such as luck in English. Compare:

• I have bad luck.
• not usually I have the bad luck unless a very specific situation is meant.

Heute means today.

In Ich habe heute Pech, it sits in the middle of the sentence, which is a very normal place for a time word in German.

The structure is:

• Ich = subject
• habe = verb
• heute = time expression
• Pech = noun/complement

This word order is completely natural.

Yes. German often allows time expressions to move, depending on emphasis.

These are both correct:

• Ich habe heute Pech.
• Heute habe ich Pech.

The second version puts more emphasis on today.

But you cannot usually say:

• Ich heute habe Pech.

because in a normal main clause, the conjugated verb must stay in second position.

Habe is the present tense form of haben for ich.

So:

• ich habe = I have

In this sentence, present tense gives the meaning I have bad luck today / I’m unlucky today.

In the meaning bad luck, Pech is normally treated as uncountable.

So you usually do not use a plural in this sense.

You say:

• viel Pech = a lot of bad luck
• kein Pech = no bad luck

not normally a plural meaning bad lucks.

It is completely idiomatic and natural.

Pech haben is one of the standard German ways to talk about being unlucky.

Other natural alternatives include:

• Ich habe heute kein Glück. = I have no luck today.
• Heute läuft es für mich schlecht. = Things are going badly for me today.

But Ich habe heute Pech is short, common, and very normal.

They are very close in meaning.

• Pech haben = to have bad luck / to be unlucky
• kein Glück haben = to have no luck

In many situations, they are interchangeable.

Examples:

• Ich habe heute Pech.
• Ich habe heute kein Glück.

Both mean that things are not going your way today.

No, that would be a different idea.

Ich habe heute Pech means I’m unlucky today, not I’m unhappy today.

If you want to say I’m unhappy today, German would more likely be:

• Ich bin heute unglücklich.

So:

• Pech haben = unlucky
• unglücklich sein = unhappy / unfortunate

Those are related ideas, but not the same.

Pech is pronounced approximately like pekh, but with the soft German ch sound after a front vowel.

A rough guide:

• P = like English p
• e = like e in bet
• ch = the soft sound heard in ich

So it is roughly:

• Pech → pekh / pehch, with a soft final sound

If you know the word ich, the ch sound is the same type of sound.

Sometimes in context, yes, but that is a freer translation.

The literal sense is specifically about luck:

• I have bad luck today
• I’m unlucky today

If several things keep going wrong, English might naturally say I’m having a bad day, and Ich habe heute Pech could fit that situation. But the German sentence itself focuses on bad luck, not on mood or the whole day in general.

It is neutral and works in both everyday informal speech and normal standard German.

You can say it to friends, coworkers, or in most ordinary situations:

• Ich habe heute Pech.

It is simple, common, and not slangy.