かさばる (kasabaru) means “bulky” | MotiTan Japanese Dictionary

More examples

この箱は、見た目よりかさばります。ko no bako wa mi ta me yo ri ka sa ba ri ma su

This box is bulkier than it looks.

Describes something that takes up more physical space than its practical use or amount might suggest.

物の体積が大きく、持ち運びや収納に多くの場所を必要とする。mono no tai seki ga ō ki ku mo chi hako bi ya shū nō ni ō ku no ba sho o hitsu yō to su ru

The native Japanese verb 嵩張る (kasabaru) combines 嵩 (kasa, "bulk") with 張る (haru, "to spread or extend").

The verb かさばる (kasabaru) often describes winter clothing, bedding, or luggage because these items occupy much storage space even when they are not especially heavy.