Translation guide
In Japanese, expressing 'another room' depends on whether you mean a different room in the same building, an additional room, or a room elsewhere. The most common and natural way is to use 別の部屋 (betsu no heya).
Referring to a room that is not the current one, often within the same house, office, or hotel.
The most common and neutral way to say 'another room' when you mean a different room. 別 means 'different' or 'separate'.
別の部屋で話しましょう。
Let's talk in another room.
This room is cold, so I'll move to another room.
Also means 'another room' but can imply 'other rooms' in general. 他 means 'other'. Slightly less specific than 別の部屋.
他の部屋も見せてください。
Please show me the other rooms as well.
Requesting or referring to one more room in addition to what you already have.
Used when you want 'one more room'. もう means 'another' or 'additional', and 一部屋 is 'one room'.
もう一部屋予約できますか？
Can I book another room?
家族が多いので、もう一部屋必要です。
We have a large family, so we need another room.
Can also be used for an additional room, but context must make it clear you want an extra one, not just a different one.
Without context, 別の部屋 usually means 'a different room'. To clearly ask for an additional room, use もう一部屋.
別の部屋もお願いします。
Another room, please. (Could be interpreted as 'a different room' or 'an additional room' depending on context.)
Referring to a room in a different location or building.
Still works, but you may need to add location context.
会議は別のビルの部屋で行います。
The meeting will be held in a room in another building.
Implies a room in someone else's house or a different place. よそ means 'another place' or 'elsewhere'. Casual.
よその部屋で寝るのは苦手だ。
I'm not good at sleeping in another person's room.
別の部屋 emphasizes 'a different room' from the current one, while 他の部屋 can mean 'other rooms' in a broader sense. In many cases they are interchangeable, but 別の部屋 is more common for 'another room'.
In Japanese, you rarely say just 'another room' without a modifier like 別の or もう. The word 部屋 alone means 'room', so you need to specify what kind of 'another' you mean.