Tone Sandhi in Chinese

Overview

Tone sandhi (变调, biàndiào) refers to the systematic tone changes that occur when certain tones appear next to each other in connected speech. While each Chinese character has a "dictionary tone," the actual pronunciation often differs due to these rules. Understanding tone sandhi is critical for sounding natural and being understood.

At the CEFR A1 level, there are three essential tone sandhi rules to master: the third-tone sandhi rule, the tone change of 不 (bù, "not"), and the tone change of 一 (yī, "one"). These rules are not exceptions -- they are regular, predictable patterns that apply consistently throughout the language.

Tone sandhi is one reason why reading pinyin with dictionary tones can sound robotic. Native speakers apply these changes automatically, and learners need to internalize them early for natural speech.

How It Works

Rule 1: Third tone + Third tone → Second tone + Third tone

When two 3rd tones appear in sequence, the first one changes to a 2nd tone:

Written	Spoken	Meaning
nǐ hǎo	ní hǎo	hello
hěn hǎo	hén hǎo	very good
xiǎo jiě	xiáo jiě	miss (young woman)

Rule 2: 不 (bù) before a 4th tone → bú

Written	Spoken	Meaning
bù shì	bú shì	is not
bù duì	bú duì	not correct
bù qù	bú qù	not go

Before 1st, 2nd, or 3rd tones, 不 stays as bù.

Rule 3: 一 (yī) tone changes

Context	Change	Example
Before 4th tone	yī → yí	一个 yí gè (one)
Before 1st/2nd/3rd tone	yī → yì	一天 yì tiān (one day)
Alone or as ordinal	stays yī	第一 dì yī (first)

Examples in Context

Chinese	Pinyin	English	Note
你好	ní hǎo	hello	3rd+3rd → 2nd+3rd
水果	shuí guǒ	fruit	3rd+3rd → 2nd+3rd
可以	ké yǐ	can	3rd+3rd → 2nd+3rd
不是	bú shì	is not	bù before 4th → bú
不好	bù hǎo	not good	bù before 3rd stays bù
不来	bù lái	not come	bù before 2nd stays bù
一个	yí gè	one (general)	yī before 4th → yí
一天	yì tiān	one day	yī before 1st → yì
一起	yì qǐ	together	yī before 3rd → yì
一年	yì nián	one year	yī before 2nd → yì
想买	xiáng mǎi	want to buy	3rd+3rd → 2nd+3rd

Common Mistakes

Not applying third-tone sandhi

• Wrong: Saying "nǐ hǎo" with two full dipping tones
• Right: Say "ní hǎo" -- the first syllable rises like a 2nd tone
• Why: Two consecutive 3rd tones are physically difficult and never occur in natural Mandarin speech.

Over-applying sandhi to written pinyin

• Wrong: Writing the changed tone in pinyin (e.g., writing "ní hǎo")
• Right: Write dictionary tones (nǐ hǎo) but pronounce with sandhi (ní hǎo)
• Why: Standard pinyin notation uses dictionary tones; sandhi is applied in speech only.

Forgetting 一 changes in different contexts

• Wrong: Always saying "yī gè" with a flat first tone
• Right: Say "yí gè" (before 4th tone, 一 becomes 2nd tone)
• Why: The tone of 一 depends entirely on the following syllable's tone.

Practice Tips

• Practice common two-syllable words with double 3rd tones first: 你好, 很好, 可以, 水果, 小姐. Say them in pairs until the sandhi becomes automatic.
• Create flashcards for 不 and 一 phrases grouped by the following tone, so you drill each pattern separately.
• When reading aloud, mark sandhi changes with a pencil above the pinyin until you apply them naturally.

Related Concepts

• Prerequisite: The Four Tones -- you must know the base tones before learning how they change in context