Especially in the sense of stingy, miserly.
What's the difference between 小气 and 小器?
I remember being told that one is more "correct", than the other, but I can't quite recall which.
The search results I've seen are just people giving their own opinions rather than citations or anything of the like.
So, what's the deal?
Today they are interchangeable as long as they mean "miserly". 小器 predates 小氣
In The Analects, Chapter 3 (論語 ‧ 八佾) (4th-3rd century BC)
子曰：管仲之器小哉。或曰：管仲儉乎
"Confucius says Guan Zhong is miserly, but someone asks if he is frugal?"
Does it make sense that 小器 means miserly? Yes and no because "miserly" and "frugal" are not identical. But 小器 also means narrow-minded or intolerant as if he has small "capacity to contain" (器) different opinions.
In Dream of the Red Chamber (18th century), Cao Xueqin used 小器 and 小氣, both meaning miserly.
In Chapter 40,
不送些玩器來與你妹妹，這樣小器。
"You didn't give those toys to your sister. So miserly"
But in Chapter 67
我又不是兩三歲的孩子，你也忒把人看得小氣了
"I'm not a child of 2-3 years old. You are mistaken that I'm miserly"
Does it make sense that 小氣 means miserly? Yes and no because 小氣 also means petty, narrow-minded and frivolous.
In 漢語大詞典, 小器 and 小氣 are synonyms. In 辭源 (1908), which focus on etymology and classical Chinese, only 小器 is listed as entry with the definition
小器——吝嗇。同‘小氣’
小器, miserly, same as 小氣
In many modern dictionaries, 小器 is omitted.
In summary, today you can safely use either 小氣 or 小器 (miserly), either 氣度 or 器度 (tolerance). Only 小氣 (simplified: 气) is more modern. Thus, in modern colloquial 小氣鬼 (a scrooge), 氣 is used.
In my opinion, the former means more like "selfish", and the latter means "small household utensils", we Chinese use it to descrip someone who can't understand others with even a small thing.
However, sometimes, "小气' can be "小器".
From Beijing's FLP C-E dictionary, 小气 and 小器 are considered identical. 小气 is described as stingy/miserly or narrow-minded, while 小器 is described as equivalent to 小气, without an explanation of its own. Using a smaller dictionary (Oxford Concise EC-CE), 小器 is not listed. To me this implies that 小器 is less common. I discussed this with two friends of mine who are formally educated in Chinese and they also think both words are the same, although interestingly one of them considered 小器 as the older word. Finally in "Standard Chinese Dictionary" the entry for 小器 is also "see 小气" with the added comment that in modern times generally 小气 is used.
Therefore it would be that 小气 is in modern usage while 小器 is less common today.
