人次: person-times, counting visits rather than people
【高04】复合量词 / measure words
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
人次 counts occurrences, not individuals: one person who comes three times counts as three 人次. It is the unit of attendance, traffic and service statistics: 景区全年接待游客两百万人次 (the site recorded two million visits over the year). The word follows the number directly, without 个: 三千人次. The noun being counted (游客, 读者, 观众, 患者) comes before the figure, after a verb such as 接待, 服务 or 参观.
Compare 人, which counts different individuals: 三千人 = three thousand people, whereas 三千人次 may be one thousand people who each came three times. The same suffix 次 appears in 架次 (the number of flights or aircraft sorties) and 车次 (the number of train or bus runs).
Register: written, journalistic and administrative (summaries, press releases, reports). In speech you would rather say 来了多少人 or 来了多少次.
Examples
景区全年接待游客两百万人次。
Jǐngqū quánnián jiēdài yóukè liǎngbǎi wàn réncì.The scenic area received two million visits over the year.
新馆开放当天，就接待读者近四千人次。
Xīnguǎn kāifàng dàngtiān, jiù jiēdài dúzhě jìn sìqiān réncì.On its opening day the new library already received nearly four thousand reader visits.
这家医院每天的门诊量大约有五千人次。
Zhè jiā yīyuàn měitiān de ménzhěnliàng dàyuē yǒu wǔqiān réncì.This hospital sees roughly five thousand outpatient visits a day.
他一个人来了三次，统计时就算三人次。
Tā yí ge rén lái le sān cì, tǒngjì shí jiù suàn sān réncì.He came alone three times, so the statistics count three person-times.
志愿者累计服务市民三千多人次。
Zhìyuànzhě lěijì fúwù shìmín sānqiān duō réncì.Volunteers have served residents on more than three thousand occasions in total.
假期里，全市地铁日均客流超过一百万人次。
Jiàqī lǐ, quánshì dìtiě rìjūn kèliú chāoguò yìbǎi wàn réncì.During the holiday the city's metro averaged over a million passenger trips a day.
Common mistakes
✗ 这座城市有一千万人次。 → ✓ 这座城市有一千万人。 (the inhabitants of a city are people, not visits).
✗ 我们三个人次去了。 → ✓ 我们三个人去了。 (人次 belongs to statistics, never to conversation).
✗ 接待了三千个人次 → ✓ 接待了三千人次 (no 个 before 人次).