Time & Dates — 日/月/年/时

A radical tour of the time namespace

Time in Chinese is structured data. There are no irregular month names, no Monday-through-Sunday word list to memorize, no AM/PM suffix rules. The calendar is a set of primitive types — 年, 月, 日 — and every date is a tuple assembled from them in strict order. The clock is another tuple: 时, 分. If you have ever sorted ISO-8601 strings lexicographically, you already know how Chinese thinks about time.

The ornament on top of this system is a handful of radicals. 日 (sun) marks everything about days and daylight; 月 (here the moon, not flesh) marks months and phases; 时 (hour) marks durations and moments. Learn the radicals, learn one numeric rule (biggest unit first, always), and the whole time vocabulary falls out as compositions.

// The time namespace.
import { day, morning, evening, bright } from "日";   // sun module
import { month, phase, bright }          from "月";   // moon module (not flesh here)
import { year, thisYear, nextYear }      from "年";   // year primitive
import { hour, when, era }                from "时";   // hour module

// Dates are tuples, always biggest-first:
type Date = [year, month, day, hour, minute];

1. The radical map

Four primitives, the whole calendar and clock. Anchors jump to each section below.

6. Days of the week

Chinese does not name the days after planets or gods. It numbers them. Monday is day one, Tuesday is day two, on to Saturday. Sunday — the outlier — takes 日 or 天 instead of a number.

The prefix 星期 literally means "star-period." A colloquial alternative, 周 (zhōu, "cycle"), gives you 周一 through 周日 — same numbering, shorter word. Both are standard. Engineer's note: this is the cleanest design decision in the whole calendar. No Wednesdays to spell wrong.

7. Months and dates

Months are even simpler than days: number plus 月. Twelve entries, zero exceptions. 一月 (January), 二月 (February), ..., 十月 (October), 十一月 (November), 十二月 (December).

For dates, Chinese writes them in strict biggest-to-smallest order — the same order a sortable ISO string uses: 年 / 月 / 日.

// 2026年4月18日 — April 18, 2026
// Read literally: "2026-year, 4-month, 18-day"
date = { year: 2026, month: 4, day: 18 };

// Spoken, same order:
// 二零二六 年 四 月 十八 日
// èr líng èr liù nián sì yuè shí bā rì

In casual speech, 日 is often replaced by 号 (hào, "number") for the day: 四月十八号 = "April 18th." 日 stays for written and formal use; 号 dominates in conversation. Both are correct.

8. Telling time

The clock has four vocabulary items: 点 (diǎn, o'clock — literally "dot"), 分 (fēn, minute — literally "divide"), 半 (bàn, half), and 刻 (kè, quarter — literally "a carved notch").

AM / PM does not exist as a suffix. Chinese splits the day into named blocks that prefix the time instead: 早上 (zǎoshang, early morning), 上午 (shàngwǔ, AM), 中午 (zhōngwǔ, noon), 下午 (xiàwǔ, PM), 晚上 (wǎnshang, evening). So 2 PM is 下午两点 — literally "afternoon two-dot." The 上/下 that mean morning/afternoon are the same 上/下 you use for "on top of" and "under" — directions of the sun.

9. Relative days

Five deictic positions around today, all sharing the suffix 天 (tiān):

The same deictic grid maps onto years: 前年, 去年, 今年, 明年, 后年. The only irregularity is that "yesterday" uses 昨 with 天 but 去 with 年.

10. Where time lives in a sentence

This is the one grammar rule to internalize. In Chinese, time expressions go before the verb, not after. English puts time adverbs at the end ("I get up at seven"); Chinese puts them right after the subject and before anything happens.

// Correct — time before the verb:
// 我 七点 起床。
// wǒ qī diǎn qǐchuáng
// "I get up at 7."
I.at(7).getUp();

// Wrong — time after the verb:
// 我 起床 七点。   ✗ ungrammatical

// Full slot order:
// [subject] [time] [place] [verb] [object]
// 我 明天 在 家 吃 饭。 — "I will eat at home tomorrow."

11. Putting it together

A few compounds that fall out of the primitives above:

12. Sentence patterns

Five sentences that fall out of this vocabulary once you know where time sits. Time always before the verb; date units always biggest-first.

// 今天 是 四月 十八 号。
// jīntiān shì sì yuè shí bā hào
// "Today is April 18th." (号 = colloquial for 日)
today === "2026-04-18";

// 我 三点 有 课。
// wǒ sān diǎn yǒu kè
// "I have class at 3." (time BEFORE 有)
me.at(3).has(class_);

// 星期一 我 上班。
// xīngqī yī wǒ shàngbān
// "On Mondays I work." (day topicalized at the front)
Mondays.forEach(() => me.work());

// 下午 两点 开会。
// xiàwǔ liǎng diǎn kāihuì
// "There's a meeting at 2 PM." (no subject needed)
schedule.at("14:00").meeting();

// 今年 我 二十 五 岁。
// jīnnián wǒ èr shí wǔ suì
// "I'm 25 this year." (岁 = years-of-age)
me.ageThisYear = 25;

13. Next steps

• Browse time & date vocabulary — filtered by tag
• Start a review session — lock in the 日 / 月 / 年 / 时 set
• See also: The Body — for the other meaning of 月
• Module 4: Composition — the full theory of radicals

The calendar and clock are the most compositional pieces of Chinese vocabulary you will ever meet. Twelve months, seven days, twenty-four hours — all built from number + unit. If you have written a date formatter, you already know the shape of this grammar.