Das Fenster ist aus Glas.

to be

Breakdown of Das Fenster ist aus Glas.

• das Fenster: the window
• das Glas: the glass
• aus: out of

Questions & Answers about Das Fenster ist aus Glas.

Why is Fenster preceded by das?

Fenster is a neuter noun in German. In the nominative singular, the definite article for neuter nouns is das.

Why is there no article before Glas in aus Glas?

When you express that something is made of a material, German typically uses aus + [Material] without an article. If you added an article (e.g. aus dem Glas), you’d imply “out of a specific glass container,” not “made of glass” in general.

Which case does aus require, and why don’t we see it on Glas?

The preposition aus always takes the dative case. Mass nouns like Glas don’t show visible endings when used without an article, so Glas looks the same even though it’s in the dative. If you included the article, you’d say aus dem Glas.

Could I say Das Fenster ist gläsern instead of aus Glas?

Yes. gläsern is a predicate adjective meaning “made of glass.” So Das Fenster ist gläsern is grammatically correct, though everyday German more often uses aus Glas to state the material.

What’s the difference between aus Glas and gläsern?