Third Tone Sandhi: When the Dipping Tone Changes
Third tone sandhi is the rule that when two third tones (the dipping tone) come in a row, the first one changes to a rising tone. So 你好 (“hello”) is written as two third tones, but you actually say it as rising + dipping — closer to “ní hǎo” than “nǐ hǎo.” Mandarin has four tones (1 high-flat, 2 rising, 3 dipping, 4 falling), and “sandhi” is just a linguistics word for a sound that shifts because of the sounds around it. Third tone sandhi is the most common tone change in everyday Mandarin. The short version: a third tone before another third tone becomes a second tone. Everywhere else, the third tone keeps its dipping shape (and in fast speech often becomes a short low dip with no rise at the end).
TL;DR
- The core rule: 3rd tone + 3rd tone → 2nd tone + 3rd tone. The first one rises.
- The written tone never changes; only the spoken tone does. Dictionaries still show 你好 as 3+3.
- A “lone” third tone, or a third tone before tones 1, 2, or 4, usually drops to a low dip (sometimes called the “half third tone”) — it doesn’t rise.
- You learn this by ear and mouth, not by memorizing a chart. A rule explains the change; it can’t produce the sound for you.
The one rule you actually need
A third tone is the “dipping” tone: the voice falls and then rises, like the slow part of a roller coaster. But two full dips in a row are physically awkward to say. So Mandarin smooths it out: the first dip turns into a rise.
Rule: When a third tone is immediately followed by another third tone, the first becomes a second (rising) tone.
Examples (written tones → spoken tones):
| Word | Meaning | Written tones | What you say |
|---|---|---|---|
| 你好 | hello | 3 + 3 | 2 + 3 (rising → dipping) |
| 很好 | very good | 3 + 3 | 2 + 3 |
| 老虎 | tiger | 3 + 3 | 2 + 3 |
| 雨伞 | umbrella | 3 + 3 | 2 + 3 |
| 我想 | I want | 3 + 3 | 2 + 3 |
Notice the pattern is always the same: only the first tone moves, and it moves up. The second third tone stays a third tone.
What about a third tone that’s NOT before another third tone?
This is where most learners get tangled. The “rises to a second tone” rule only fires before another third tone. In every other position, the third tone does something different:
- Before tone 1, 2, or 4: the third tone usually becomes a low dip with no rise — it goes down and stops. This is often called the half third tone. Example: 老师 (lǎoshī, “teacher”) — the 老 dips low but doesn’t bounce back up.
- At the end of a sentence or said alone: you may hear the full dip-and-rise, especially in careful or emphatic speech. In casual speech it’s often still just a low dip.
So a third tone almost never sounds like the full “down-then-up” cartoon shape in real conversation. It either rises fully (sandhi, before another third tone) or dips low and stays (everywhere else). That single insight fixes a huge amount of robotic-sounding Mandarin.
Three or more third tones in a row
When three third tones stack up, where the change lands depends on how the words group together — and that’s why a flat “memorize the rule” approach falls short.
- 我很好 (“I’m very good”) groups as 我 + 很好. 很好 becomes 2+3 first, then 我 sits before a rising tone, so it often becomes 2+2+3.
- A different phrase with a different word boundary changes where the shift happens.
The practical takeaway: you don’t compute this in your head mid-sentence. Native and fluent speakers chunk by meaning and the tones fall into place. You get there by hearing real phrases and copying them — which is exactly why drilling isolated rules tends to stall.
Q&A
Does the written tone (the Pinyin or tone mark) change too? No. Dictionaries and textbooks keep 你好 as third + third. Sandhi is a spoken rule. This mismatch between page and mouth is one reason tone marks alone don’t teach pronunciation — they show the “dictionary” tone, not what you say. (More on that in learning Chinese without Pinyin.)
Is 不 (bù) or 一 (yī) third tone sandhi? No — those words have their own separate tone-change rules and are not part of third tone sandhi, which only involves third tones.
Why does this matter for my grade and for being understood? Because tones carry meaning. Under HSK 3.0 there’s now a mandatory speaking section where tones directly affect your score, so getting sandhi natural-sounding is no longer optional. See HSK 3.0 speaking and tones.
Why a rule isn’t enough (and what actually works)
You can read this whole page, nod along, and still say a flat, foreign-sounding 你好. That’s not a knowledge gap — it’s a motor-skill gap. Knowing the rule lives in your head; producing the rising-then-dipping contour lives in your mouth and ear.
This is the same reason common tools stall on tones:
- Streak apps reward showing up, not accuracy. You can tap the right answer with the wrong tone forever.
- AI tutors usually can’t reliably hear your specific tone error, so they praise output a human teacher would correct.
- Pinyin and tone marks describe tones on paper but never reach the mouth — and as we just saw, they don’t even show the sandhi.
(We go deeper on this in why Chinese tones are so hard, the parent guide to this whole cluster.)
Tone Fluent teaches English-speaking adults Chinese from zero to HSK4 with live, small-group classes. Instead of Pinyin or tone marks, it uses the Rainbow method: a numbered 1–5 pronunciation system with a simple See it → Hear it → Say it loop, so you train tones with your ears and mouth, not just your eyes. It’s built on 20+ years of curriculum development. For third tone sandhi specifically, that means hearing the rising-first 你好, then saying it back and getting corrected by a live teacher until the contour is automatic.
Practice this without overthinking
- Say 你好 as “rising, then dipping.” Exaggerate the rise at first.
- Try 很好 and 老虎 the same way — first syllable up, second syllable down-low.
- Now contrast with 老师 (lǎoshī): here the 老 stays low and flat-ish, no rise. Feel the difference between “rises” and “dips and stops.”
- Repeat out loud. Tones are a physical habit; reading them is not the same as owning them.
If you want a teacher to actually hear your tones and fix the ones you can’t hear yourself, the free 3-week bootcamp (12 live hours) is the place to start — join the next bootcamp. From there, the full course takes you from zero to HSK4 in live class.
Next in this cluster: why Chinese tones are so hard — and how to master them.