In my Chinese classes, I occasionally found that most my foreigner students are confused about the useage of 必要 (bì yào) and 必需 (bì xū) , it is hard for them to tell the difference and when to use the two words.
Hence I would like to have a discussion in this article about how to say "need" properly in Chinese. Usually, there are four ways Chinese people are used to express "need", namely: 需要 (xū yào), 必要 (bì yào), 必须 (bì xū), 必需 (bì xū)。
需要 (xū yào) is a high frequency Chinese word, which is generally means "to need", to want", to demand"...
天凉了，出门需要加件衣服了。(Tiān liáng le, chū mén xū yào jiā jiàn yī fú le.)
It is getting cold, and we need put more clothes on to get out.
必要 (bì yào) often appears in the negative sentences. Also it often follow after the negative word "没 (méi)" or "没有 (méi yǒu)", say "没必要 (méi bì yào)" or "没有...必要(méi yǒu...bì yào)" which equaling "it is no need" or "it is not nessary" in English.
It is no need (not necessary) for you to apologize to me.
必须 (bì xū) is generally used as the adverbial part of a sentence, implying some sort of order tone like "must". Basically you use this when you want to emphasize the degree of "need".
你必须一个人去处理这件事。(Nǐ bì xū yí gè rén qù chú lǐ zhè jiàn shì.)
You must handle it by youself.
必需 (bì xū) is a little bit formal, indicating something is indispensable. It is often connected with "所 (suǒ)" revealing a kind of condition.
空气和水是每个人所必需的。(Kōng qì hé shuǐ shì měi gè rén suǒ bì xū de.)
Air and water are necessary for everybody.
It is a great way to remember some example sentences to differ the synonyms, especially when you learn Chinese online. Below are a group of example sentences to help you to easily remember the four usages of "need":
我需要你的帮助。(Wǒxū yào nǐ de bāng zhù.)
I need you help.
我没有帮助你的必要。(Wǒ méi yǒu bāng zhù nǐ de bì yào.)
It is no need (not necessary) for me to help you.
你必须帮助我。(Nǐ bì xū bāng zhù wǒ.)
You must help me.
我要成功的话，你的帮助是必需的。(Wǒ yào chéng gōng de huà, nǐ de bāng zhù shì bì xū de.)
Your help is needed if I want to be successful.
