кстати vs между прочим

kстати vs mezhdu prochim — by the way vs incidentally

What it really means

Кстати introduces a relevant aside, a new conversational point, or something useful to mention. Между прочим also means “incidentally,” but can highlight an overlooked fact and sometimes carries a mildly corrective or pointed tone. Both are commonly introductory adverbs; punctuation depends on whether they are parenthetical or integrated into the sentence.

Examples in natural speech

Кстати, ты получил моё письмо?
By the way, did you get my letter?
Кстати, завтра музей закрыт.
By the way, the museum is closed tomorrow.
Между прочим, он уже всё оплатил.
Incidentally, he has already paid for everything.
Она, между прочим, отлично говорит по-русски.
She speaks Russian very well, by the way.
Это кстати пригодится в поездке.
This will come in handy on the trip.

Common mistakes

Do not assume кстати only means “by the way”: «кстати пригодиться» means “to come in handy.” Do not add commas mechanically when an adverb is part of the predicate, and do not use между прочим if its pointed undertone would sound rude.

Memory tip

Кстати opens a useful tangent; между прочим draws attention to a fact someone may have overlooked.

Frequently asked questions

Does кстати always need commas?

No. As an aside it is often separated («Кстати, …»), but in «это кстати» it is an ordinary adverb meaning “useful/right for the occasion.”

Is между прочим sarcastic?

It can be neutral, but emphasis and context may make it sound like a pointed reminder or correction.

Can these words change the topic?

Кстати commonly introduces a related new topic; между прочим usually adds a fact to the current topic or argument.

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