Learn Hardcore German: Ich lege mein Gepäck in den Kofferraum.

We use in + accusative (den) because the phrase expresses movement into the trunk (Wohin?). German prepositions like in take the accusative case when they indicate motion. If you wanted to say “inside the trunk” (location, Wo?), you’d use the dative: im Kofferraum (in + dem = im).

Why do we use legen and not stellen when we say Ich lege mein Gepäck in den Kofferraum?

legen means “to lay” something horizontally, whereas stellen means “to place” something upright (vertically). Luggage typically lies flat in the trunk, so legen is the natural choice. If you were placing a tall object upright, you’d use stellen instead.

What gender is Kofferraum, and how do I know it becomes den Kofferraum?

Kofferraum is masculine in German (der Kofferraum). Because in here shows movement (Wohin?), it takes the accusative case. The masculine singular article der changes to den, so you get in den Kofferraum.

Why do we say mein Gepäck and not meine Gepäcke?

Gepäck is an uncountable (mass) noun in German—it doesn’t have a plural form. You always use the singular Gepäck. Mein agrees with neuter singular in the nominative case: mein Gepäck.

Could I say Mein Gepäck lege ich in den Kofferraum? Does the meaning change?

Yes, you can. That’s topicalization: you move Mein Gepäck to the front to emphasize it. The verb lege stays in the second slot, and the rest follows. The core meaning (“I put my luggage in the trunk”) stays the same, but you’re highlighting mein Gepäck.

Could I use packen instead of legen here?

You could say Ich packe mein Gepäck in den Kofferraum, but packen means “to pack” or “to stow” (arrange things neatly inside). Legen simply describes the action of placing or laying something down without implying organization. Use packen if you want to stress arranging items; use legen for the neutral “put it down.”

Could I replace Gepäck with Koffer?

Yes. Koffer means “suitcase” and is countable. If you mean one specific suitcase, say Ich lege meinen Koffer in den Kofferraum. Here Koffer is masculine, so in the accusative you use meinen Koffer.