ちなみにIncidentally; as a related side note
ちなみに introduces a brief extra fact connected to what was just mentioned. The detail is relevant to the current topic but not essential to the main point.
How the connection works
The added sentence should answer a small secondary question that naturally arises from the current topic: another number, a practical detail, a piece of background, or an interesting fact. If the extra sentence were removed, the main explanation or story would still work.
A related fact in explanatory writing
この美術館は、かつて市役所として使われていた。ちなみに、建物自体も文化財に指定されている。
This art museum was once used as city hall. Incidentally, the building itself is also designated as a cultural property.
AnalyzeThe building’s official status is clearly connected to the museum, but it is not necessary to understand the first sentence.
A practical follow-up in polite conversation
来週の説明会は午後二時からです。
Next week’s information session starts at two in the afternoon.
Analyzeありがとうございます。ちなみに、会場に駐車場はありますか。
Thank you. By the way, is there parking at the venue?
AnalyzeThe question about parking is secondary, but it remains directly connected to attending the session.
Related aside, new topic, formal supplement, or exception?
ちなみに adds a light side fact within the current topic. ところで moves to a genuinely new topic. なお introduces a relevant supplement in a more formal or businesslike style. ただし gives a condition or exception that changes how the preceding statement applies.
来月、京都で学会があります。ちなみに、会場は京都駅の近くです。
There is a conference in Kyoto next month. Incidentally, the venue is near Kyoto Station.
AnalyzeThe venue is a secondary detail about the same conference.
来月、京都で学会があります。ところで、昨日の試合は見ましたか。
There is a conference in Kyoto next month. By the way, did you watch yesterday’s game?
AnalyzeThis is a genuine topic switch, so ところで is appropriate.
The expanded form
ちなみに言うと works like the simple connective but explicitly frames the next sentence as something the speaker is adding. In most situations, the shorter form is sufficient.
More examples
この講座はオンラインでも受講できます。ちなみに、教材費は受講料に含まれています。
This course can also be taken online. Incidentally, the cost of the materials is included in the course fee.
Analyze田中さんは北海道の出身です。ちなみに、大学も札幌でした。
Ms. Tanaka is from Hokkaido. Incidentally, she also attended university in Sapporo.
Analyze明日の会議は十時に始まります。ちなみに、資料は今朝メールで送りました。
Tomorrow’s meeting starts at ten. By the way, I sent the materials by email this morning.
Analyzeこのホテルは空港から電車で十五分です。ちなみに、最寄り駅からは無料バスも出ています。
This hotel is fifteen minutes from the airport by train. Incidentally, there is also a free bus from the nearest station.
Analyze今回の調査には百二十人が参加した。ちなみに、前回の参加者は五十人だった。
One hundred and twenty people participated in this survey. For reference, the previous survey had fifty participants.
Analyzeこの町には古い橋が三つ残っている。ちなみに言うと、最も古い橋は江戸時代に造られた。
Three old bridges remain in this town. Incidentally, the oldest one was built in the Edo period.
Analyze