What is the difference between 楼 and 层?

The short answer is that 楼lóu (lóu) means “floor”, while 层céng (céng) is a classifier meaning “storey” or “layer”.

If you want to know more about classifiers, check out my post on Chinese Classifiers: What are they and how to use them as well as my complete list of Mandarin Chinese classifiers and measure words.

Suppose you wanted to talk about the fifth floor of a building:

第dì五wǔ层céng楼lóu
dì wǔ céng lóu
(the) fifth storey floor

Breaking this down:

• 第dì五wǔ (dì wǔ) means “fifth”
• 层céng (céng) means “storey”
• 楼lóu (lóu) means “floor”

You can shorten this sentence by leaving off characters, for example:

五wǔ层céng
wǔ céng
storey five (fifth storey)

五wǔ楼lóu
wǔ lóu
floor five (fifth floor)

第dì五wǔ层céng
dì wǔ céng
(the) fifth storey

第dì五wǔ楼lóu
dì wǔ lóu
(the) fifth floor

It is more common to simply say 五wǔ楼lóu or 五wǔ层céng, however all combinations are used.

层céng (céng) also has the meaning “layer”, while 楼lóu (lóu) does not, so while you can say 三sān层céng蛋dàn糕gāo (sān céng dàngāo), meaning “three layer (tier) cake”, it is incorrect to say 三sān楼lóu蛋dàn糕gāo (sān lóu dàngāo). Anywhere in English where you see the word layer, 层céng (céng) is normally the equivalent in Chinese, for example “adhesive layer” 粘zhān合hé层céng (nián hé céng) or ‘network layer” 网wǎng络luò层céng (wǎngluò céng).