Fastän jag är trött vill jag läsa en bok.

Fastän means although, even though, or though. It introduces a contrast:

• Fastän jag är trött = Although I am tired
• vill jag läsa en bok = I want to read a book

So the whole sentence expresses: being tired does not stop the speaker from wanting to read.

Because fastän introduces a subordinate clause. In Swedish subordinate clauses, the normal subject-verb order is used:

• jag är trött = I am tired

So after fastän, you do not invert the verb and subject.

Compare:

• Main clause: Jag är trött.
• Subordinate clause: fastän jag är trött

This is because of Swedish V2 word order in main clauses.

The whole first part, Fastän jag är trött, comes first in the sentence. When something comes before the main clause, the finite verb of the main clause must come second. That gives:

• Fastän jag är trött vill jag läsa en bok.

Not:

• Fastän jag är trött jag vill läsa en bok.

A useful way to think about it:

1. First position: Fastän jag är trött
2. Second position: vill
3. Then the subject: jag

Yes. Fastän is a subordinating conjunction. It links a subordinate clause to the main clause and shows contrast.

Other Swedish conjunctions of this type include:

• att = that
• om = if/whether
• eftersom = because
• när = when
• fastän = although

Because vilja is a modal verb here, and modal verbs in Swedish are followed directly by the infinitive without att.

So you say:

• jag vill läsa = I want to read

Not:

• jag vill att läsa

This is similar to English I want to read, where no extra word is needed before read in this structure.

Other modal verbs work the same way:

• jag kan läsa = I can read
• jag ska läsa = I will read
• jag måste läsa = I must read

Läsa is the infinitive form, meaning to read.

After vill, Swedish uses the infinitive:

• vill läsa = want to read

So:

• vill = finite verb
• läsa = infinitive

This is a very common pattern in Swedish.

In Swedish, when you mean a book, you normally use the indefinite article:

• en bok = a book

Using just bok by itself would usually sound incomplete in a sentence like this.

So:

• läsa en bok = read a book

Since bok is a common-gender noun, it takes en, not ett.

Swedish nouns belong to two grammatical genders:

• en-words
• ett-words

Bok is an en-word, so it becomes:

• en bok

You simply have to learn the gender of each noun as part of the vocabulary.

Here, trött agrees with jag, which is singular, so trött is the correct form.

The adjective can change in other contexts. For example:

• Jag är trött. = I am tired.
• Vi är trötta. = We are tired.

So yes, the adjective can change, but in this sentence trött is the right singular/common form.

Usually, no comma is necessary in Swedish here:

• Fastän jag är trött vill jag läsa en bok.

A comma is sometimes possible for clarity or style, especially in longer sentences, but it is often omitted in normal Swedish writing.

So the version without a comma is perfectly natural.

Yes. That is also correct.

• Fastän jag är trött vill jag läsa en bok.
• Jag vill läsa en bok fastän jag är trött.

The meaning is basically the same, but the emphasis changes a little.

If you start with Fastän jag är trött, you highlight the contrast first.
If you start with Jag vill läsa en bok, you present the main idea first.

Yes, it is common and natural. But in everyday speech, some speakers may also use:

• fast = though/although
• även om = even if/even though

For example:

• Fast jag är trött vill jag läsa en bok.
• Även om jag är trött vill jag läsa en bok.

These are similar, but fastän is a clear and standard written choice.

The main clause verb is vill.

That is important because the sentence has two verbs:

• är in the subordinate clause
• vill in the main clause

The structure is:

• Subordinate clause: Fastän jag är trött
• Main clause: vill jag läsa en bok

So the core statement is jag vill läsa en bok, and the first part adds contrast.

Because the sentence contains two clauses:

1. Fastän jag är trött
   This is a subordinate clause, and är is its verb.

2. vill jag läsa en bok
   This is the main clause, and vill is its finite verb.

Swedish, like English, often uses one finite verb per clause. Since this sentence has two clauses, it has two finite verbs.

The first clause is quite close to English:

• Fastän jag är trött = Although I am tired

But the second part differs because Swedish keeps the finite verb in second position in the main clause:

• Swedish: Fastän jag är trött vill jag läsa en bok
• English: Although I am tired, I want to read a book

English keeps I want, but Swedish changes it to vill jag because of V2 word order.

That inversion is one of the most important things to notice in this sentence.