Translation guide
A data storage device used in computers. In Japanese, the term is usually expressed with the loanword ハードディスク or the abbreviation HDD.
Referring to the physical storage device inside a computer or external enclosure.
The most common and direct translation. Used in both technical and everyday contexts.
ハードディスクの容量が足りません。
The hard disk is running out of space.
外付けハードディスクを買いました。
I bought an external hard disk.
Abbreviation for Hard Disk Drive. Common in technical contexts, product specs, and among enthusiasts.
HDDからSSDに換装しました。
I replaced the HDD with an SSD.
Full form of HDD. Rarely used in conversation; mostly seen in formal documentation.
ハードディスクドライブの故障が原因です。
The cause is a hard disk drive failure.
Talking about the amount of storage or comparing with other storage types like SSD.
Used when discussing storage space or type, often in contrast with SSD.
このパソコンはハードディスクが1TBです。
This PC has a 1TB hard disk.
ハードディスクよりSSDのほうが速いです。
SSDs are faster than hard disks.
In casual conversation, ハードディスク is perfectly natural. HDD is common in written specs or when comparing with SSD. Avoid the full ハードディスクドライブ unless in a formal report.