房间太小了 The room is too small. 房间很小 The room is very small. 房间多小啊 一般是加“多”有感叹的意思 How small the room is .一般"多"的后面要加个"啊" 表现感叹语气 从程度（degree）上来说"太"＞"很" 而"多"的程度大小要看使用的场合和使用的语气等

程度副词，多用于感叹。 太——太有意思啦！太美妙啦！太好了！太棒了！ 很——很有意思。很美妙。很好，很棒。 多——多有意思呀？！多美妙呀？！多好呀？！多棒喔？！ 另外再给你一个北方口语（忒=太） 忒——忒有意思啦！忒美妙啦！忒好了！忒棒了！ （以上例句都表示赞叹） ———————————————————————————————— 房间太小了！（表示不合适、不满意） 房间很小。（不一定不合适) 房间多小呀！（不合适，但不一定不满意） 房间多么小呀？！（不合适，不满意）

if you use 房间很小了 to describe the small size of a certain room. i think it's fine but it's not proper enough. this sentence 房间很小了 has a potential meaning that the room had been arranged by somebody and become small finally. as well that, i don't suggest you to use the sentence 房间多小了 either. actually, the meaning of 房间多小了 is that "what is the size of that room?" after a certain period, a decoration or something else. well, my friend, i believe you can figure this out all by yourself in the Chinese chat. i wish i could help.

the room is small: 1.房间太小了 2.房间很小 3.这个房间比那个房间小多了 the room is very small.这个房间非常小 the room is so small.这个房间是如此的小

“房间很小”can't use the "了”。this Declarative sentence "房间太小”is Exclamatory Sentences ，add the "了”can increase effect.