Ég skal gera þetta sjálf.

Skal is the 1st person singular present form of skulu.

In this sentence, Ég skal gera þetta sjálf means something like I’ll do this myself or I shall do this myself. The nuance is often stronger than a simple future: it can sound like a promise, an offer, a firm decision, or reassurance.

A useful comparison:

• Ég skal gera þetta. = I’ll do this. / I’ll take care of this.
• Ég mun gera þetta. = a more neutral I will do this
• Ég ætla að gera þetta. = I intend to do this

Also, unlike English shall, Icelandic skal is not especially old-fashioned. It is a normal modern word.

Because skulu is a modal verb, and modal verbs are followed by an infinitive.

So:

• skal = conjugated modal verb
• gera = infinitive, to do / to make

This works much like English:

• I shall do
• I will do

You do not conjugate gera here. So Ég skal gera þetta is correct, but Ég skal geri þetta would be wrong.

Þetta means this and is the direct object of gera.

So the structure is:

• Ég = I
• skal gera = will do
• þetta = this
• sjálf = myself / personally

In other words, þetta is the thing being done.

Grammatically, it is in the accusative here because it is the direct object. But in the neuter singular, the nominative and accusative forms are the same, so it still appears as þetta.

It agrees with ég, not with þetta.

That is a very common point of confusion, because þetta is neuter and sjálf can also look like a neuter form. But in this sentence, sjálf refers to the speaker: I myself.

Since ég does not show gender on its own, sjálf tells you that the speaker is female.

So:

• female speaker: Ég skal gera þetta sjálf.
• male speaker: Ég skal gera þetta sjálfur.

The form is nominative singular because it matches the subject ég.

Because here sjálf is not the direct object. It is an emphatic word attached to the subject: I myself.

English uses myself both for emphasis and for true reflexive object meaning, but Icelandic often separates those ideas more clearly.

In your sentence:

• Ég skal gera þetta sjálf = I will do this myself

Here sjálf emphasizes the subject ég.

But if myself were actually the object, you would use a reflexive/object form such as:

• Ég sá sjálfa mig. = I saw myself.

So the sentence is not saying I will do myself. It is saying I myself will do this.

In this sentence, it mainly means myself or personally.

So Ég skal gera þetta sjálf means:

• I’ll do this myself
• I’ll do this personally

Depending on context, English might also translate it as I’ll do this by myself, but that is not always the main point. The emphasis is often that I, rather than someone else, will do it.

If you specifically want to stress being alone, Icelandic may use other expressions too, depending on context, such as ein or á eigin spýtur.

So here, think first of myself / personally, not necessarily alone.

Putting sjálf at the end is a very natural way to place the emphasis there.

So:

• Ég skal gera þetta sjálf. = natural, common
• emphasis falls strongly on sjálf

But Icelandic word order is somewhat flexible, and moving sjálf can change what is highlighted:

• Ég skal sjálf gera þetta. = I myself will do this
• Sjálf skal ég gera þetta. = stronger, more marked, sometimes more literary or dramatic

The version with sjálf at the end is probably the most straightforward everyday pattern here.

Yes.

• Ég skal gera þetta. = I’ll do this.
• Ég skal gera þetta sjálf. = I’ll do this myself.

Leaving out sjálf removes the extra emphasis. With sjálf, the sentence can imply contrast, for example:

• someone else offered to do it
• someone thinks you need help
• you want to make it clear that you will handle it personally

So sjálf adds emphasis, not basic sentence structure.

A man would normally say:

• Ég skal gera þetta sjálfur.

The difference is only in the form of sjálfur, which agrees with the speaker’s gender:

• sjálf = feminine singular
• sjálfur = masculine singular

So the rest of the sentence stays the same.

In natural English, I will do this myself is usually the best translation.

Even though skal is historically related to shall, modern English shall often sounds formal or old-fashioned, while Icelandic skal does not.

So for a learner, the safest practical understanding is:

• Ég skal gera þetta sjálf. = I’ll do this myself.

Just remember that Icelandic skal often carries a tone of determination, promise, or willingness that is stronger than a plain future statement.