Pinyin basics · 8 min read
Pinyin Tone Marks: Placement Rules and Tone Sandhi
Where the tone mark goes, how to type ǎ and ǜ on any keyboard, and the sandhi rules that change how tones sound but never how they are written.
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Tone marks look like a small detail and behave like a large one. Put the mark on the wrong vowel and you have written something non-standard; drop it entirely and you have written something ambiguous.
This guide covers the three things that actually cause trouble: which vowel carries the mark, how to type the marks without fighting your keyboard, and why the tone you write is often not the tone you say.
The four tones and the neutral tone
Mandarin tones are pitch contours over a syllable, conventionally described on a five-point scale where 5 is the top of your comfortable range and 1 the bottom.
| Tone | Mark | Contour | Description | Example |
|---|---|---|---|---|
| First | ā | 55 | High and level, held steady | 妈 mā — mother |
| Second | á | 35 | Rising, like a question in English | 麻 má — hemp |
| Third | ǎ | 214 | Dips low, then rises | 马 mǎ — horse |
| Fourth | à | 51 | Sharp fall from high to low | 骂 mà — to scold |
| Neutral | a | — | Short, light, no contour | 吗 ma — question particle |
Where the tone mark goes
A tone mark sits on exactly one vowel per syllable. The rule is short enough to memorise in a minute and covers every case:
- If there is an a, the mark goes on the a. hǎo, xiàng, kuài.
- Otherwise, if there is an o or an e, the mark goes on that. duō, xiè, gǒu. (No syllable contains both o and e.)
- Otherwise the syllable has only i, u or ü. The mark goes on the last one. liù, duì, guī.
- The single exception: in iu the mark goes on the u, and in ui it goes on the i — which is what 'the last one' produces anyway, so it is really just a confirmation.
- When i takes a mark, the dot is replaced: ī í ǐ ì.
| Syllable | Mark goes on | Why | Result |
|---|---|---|---|
| hao | a | Rule 1: a wins | hǎo |
| xie | e | Rule 2: no a, so e | xiè |
| guo | o | Rule 2: no a, so o | guó |
| liu | u | Rule 3: last of i/u | liù |
| dui | i | Rule 3: last of i/u | duì |
| nü | ü | Rule 3: only vowel | nǚ |
Typing tone marks
The pragmatic answer for most people is to write in tone numbers and convert. Type ni3 hao3, run it through a converter, and paste the result. This is faster than any keyboard method once you are typing more than a few words.
If you need to type marks directly, every platform has a route. On macOS, adding the ABC Extended input source gives you dead keys: Option+A for macron, Option+E for acute, Option+V for caron, Option+` for grave, each followed by the vowel. On Windows, the Microsoft Pinyin IME has a tone-mark mode, and third-party layouts such as the Pinyinput tool handle it directly. On Linux, the Compose key covers macron and caron combinations.
For ü specifically, most Chinese input methods accept v as a substitute, since v is unused in pinyin. Typing nv3 gives you nǚ.
In HTML, the marks are ordinary Unicode characters and need no entities as long as the page is UTF-8. In LaTeX, the pinyin package or CJK bundle handles them.
Tone sandhi: written tone vs spoken tone
Mandarin changes tones in connected speech, and these changes are almost never reflected in writing. This trips up learners who assume pinyin is a phonetic transcription of what is actually said — it is a transcription of citation tones.
The third tone rule is the most important. Two third tones in a row: the first becomes a second tone. 你好 is written nǐ hǎo and pronounced ní hǎo. 很好 is written hěn hǎo and pronounced hén hǎo. Three in a row depends on phrasing. And a third tone before any other tone is usually reduced to just its low-falling first half rather than the full dip-and-rise — this 'half third tone' is what you hear in 好吃 hǎochī.
不 bù drops to bú before a fourth tone: 不是 is bú shì, 不对 is bú duì. Everywhere else it stays fourth.
一 yī is more elaborate. Alone or at the end of a phrase, and in ordinal numbers, it is first tone. Before a fourth tone it becomes yí — 一个 yí gè. Before first, second or third tones it becomes yì — 一起 yìqǐ, 一年 yì nián.
Dictionaries and textbooks vary on whether they show the sandhi form for 不 and 一. Most show the sandhi tone for these two because the change is regular and predictable; almost none show it for the third tone rule, because that would obscure the underlying word.
Why the written form keeps the citation tone
It would seem more helpful to write what is actually said. There are good reasons not to.
First, the sandhi tone depends on context. 好 is third tone, but in 好好 the first one surfaces as second. If you wrote the surfaced tone you would be spelling the same word differently in different sentences, which makes dictionary lookup and pattern recognition much harder.
Second, native speakers perceive the underlying tone. Ask a Chinese speaker what tone 你 has in 你好 and they will say third, because that is the word's tone — the sandhi is an automatic phonetic process, not a change of identity.
Third, the rules are regular enough to apply automatically once internalised. Writing citation tones and applying sandhi in production is the same thing native speakers do, and it is what lets you generalise to words you have not met before.
Key takeaways
- Mark placement: a wins, then o or e, otherwise the last of i/u/ü.
- Tone numbers carry identical information and are far easier to type.
- Two third tones in a row: the first is pronounced as a second tone.
- 不 becomes bú before a fourth tone; 一 becomes yí before fourth and yì before others.
- Pinyin writes citation tones, not the tones actually produced in connected speech.
Frequently asked questions
Does the neutral tone get a mark?
No. The neutral tone is written with no diacritic at all — 妈妈 is māma, 谢谢 is xièxie. In tone-number notation it is written as 5 or simply omitted.
Is it acceptable to write pinyin without tone marks?
For typing input, yes — every IME accepts toneless pinyin. For study material, no. Toneless pinyin is genuinely ambiguous and learners who study from it acquire tonally flat pronunciation that is hard to correct later.
Should I write 你好 as nǐ hǎo or ní hǎo?
Write nǐ hǎo. That is the standard orthography and what every dictionary uses. Pronounce it ní hǎo. The gap between the two is the sandhi rule doing its job.