<p>Since you are not asking what is the difference between '必定' and '一定' or the difference between '必' and '定', I would just go ahead and state the  difference between '必'  and '一定'</p>
<p>From my answer to this question:</p>
<blockquote>
<p><a href="https://chinese.stackexchange.com/questions/32089/meaning-of-%e7%9a%84-and-%e4%b9%8b-when-both-are-used-in-the-same-sentence">Meaning of 的 and 之 when both are used in the same sentence</a></p>
<p><em>之 is the classical Chinese counterpart of 的 in modern Chinese</em></p>
</blockquote>
<p>必 is the classical Chinese counterpart of 一定/必定 in modern Chinese</p>
<p>Examples:</p>
<blockquote>
<p>Classical Chinese style: &quot;兵家(<strong>必</strong>)爭之地&quot;</p>
<p>Modern Chinese: &quot;軍事決策者(<strong>一定</strong>/ <strong>必定</strong>)會去爭奪的地點&quot;</p>
</blockquote>
<p>~</p>
<blockquote>
<p>Classical Chinese style: &quot;中此毒者(<strong>必</strong>)死&quot;</p>
<p>Modern Chinese: &quot;中了這個毒的人(<strong>一定</strong>/<strong>必定</strong>)會死亡&quot;</p>
</blockquote>
<p>~</p>
<blockquote>
<p>Classical Chinese style: &quot;日軍稱三月內(<strong>必</strong>)亡中國&quot;</p>
<p>Modern Chinese: &quot;日本軍方宣稱三個月內(<strong>一定</strong>/<strong>必定</strong>)能覆亡中國&quot;</p>
</blockquote>
<p><em>'必' on its own has other meaning and usage, but the question only asked for the comparison between '必' and '一定'. The most obvious difference between the two is as this answer stated.</em></p>
<p><strong>Notice:</strong> Actually, I should say '必' is more <strong>literary</strong> and '一定' is more <strong>colloquial</strong> because classical style wording appear mostly in writing</p>

CC BY-SA 4.0
2018-11-28T13:11:42.633Z
Are they classical Chinese? Not just formal form?
炸鱼薯条德里克
CC BY-SA 4.0
2018-11-28T13:17:59.723Z
@神秘德里克  Classical Chinese style is embedded in modern Chinese. We don't often hear pure classical speech, but classical style phrases appear in writing a lot. Day to day conversation is made up of  'colloquial, literary, classical phrases and  slang'
Tang Ho
CC BY-SA 4.0
2018-11-28T13:46:58.043Z
@神秘德里克 1."請老師(垂鑒)"   2. "請老師(過目)"  3.請老師(看看). -- 垂鑒  is a formal term (to show respect), 過目 is a literary term (base on classical style) , 看看 is a colloquial term. The sentence: "天津是兵家必爭之地" is a mix of classical  and standard Chinese, and it is totally normal in modern Chinese writing and speech. But it is not considered 'formal form'
Tang Ho
CC BY-SA 4.0
2018-11-28T10:04:57.997Z
2018-12-18T10:04:48.257Z
2020-06-17T09:50:11.587Z
Tang Ho
<p>It is the same, you can interchange the two.</p>

CC BY-SA 4.0
2018-11-28T17:07:55.690Z
Yes, they mean the same, but they are for different styles (literary and colloquial), you cannot freely interchange them. When you replace  '必' with '一定' , you have to change the rest of the sentence sometimes. For example: "(必)無好果" =  "(一定)沒有好結果" ; you cannot just replace '必' with '一定' and write " 一定無好果"
Tang Ho
CC BY-SA 4.0
2018-11-28T16:59:25.123Z
2018-11-28T16:59:25.123Z
user614287
<ul>
<li>我必须去 I must go there (because of some reasons).</li>
<li>我一定去 I must go there (really want to, no matter what) .</li>
</ul>

<p>They all mean you must go there sometime in the future.</p>

<p>However, 一定 is subjectively, 必 is objectively. </p>

CC BY-SA 4.0
2018-11-28T06:05:37.867Z
2018-11-28T06:05:37.867Z
Kacie Chen
<p>Both words kinda mean <em>“must, necessarily, certainly”</em>. Can someone explain the differences between the two?</p>

CC BY-SA 4.0
2018-11-28T08:24:44.260Z
Are you asking what is the difference between '必定' and '一定' or the difference between  '必' and '定'?
Tang Ho
CC BY-SA 4.0
2018-12-19T08:34:51.353Z
They are the same meaning. But I said "一定" more than "必" , "必然", "必定"  in general.
AechoLiu
<word-choice><mandarin><usage>
Difference between 必 and 一定
# Difference between 必 and 一定

(Asked by: username_0 on 2018-11-28)

Both words kinda mean *“must, necessarily, certainly”*. Can someone explain the differences between the two?

**Tags:** word-choice, mandarin, usage

> **Comments:**
> **username_1**: Are you asking what is the difference between '必定' and '一定' or the difference between  '必' and '定'?  
> **username_2**: They are the same meaning. But I said "一定" more than "必" , "必然", "必定"  in general.  

---

## 3 answers

### Answer by username_1 on 2018-11-28. Score: 5

Since you are not asking what is the difference between '必定' and '一定' or the difference between '必' and '定', I would just go ahead and state the difference between '必' and '一定'

From my answer to this question:

> [Meaning of 的 and 之 when both are used in the same sentence](https://chinese.stackexchange.com/questions/32089/meaning-of-%e7%9a%84-and-%e4%b9%8b-when-both-are-used-in-the-same-sentence)
>
> *之 is the classical Chinese counterpart of 的 in modern Chinese*

必 is the classical Chinese counterpart of 一定/必定 in modern Chinese

Examples:

> Classical Chinese style: "兵家(**必**)爭之地"
>
> Modern Chinese: "軍事決策者(**一定**/ **必定**)會去爭奪的地點"

~

> Classical Chinese style: "中此毒者(**必**)死"
>
> Modern Chinese: "中了這個毒的人(**一定**/**必定**)會死亡"

~

> Classical Chinese style: "日軍稱三月內(**必**)亡中國"
>
> Modern Chinese: "日本軍方宣稱三個月內(**一定**/**必定**)能覆亡中國"

*'必' on its own has other meaning and usage, but the question only asked for the comparison between '必' and '一定'. The most obvious difference between the two is as this answer stated.*

**Notice:** Actually, I should say '必' is more **literary** and '一定' is more **colloquial** because classical style wording appear mostly in writing

> **Comments:**
> **username_3**: Are they classical Chinese? Not just formal form?  
> **username_1**: @神秘德里克  Classical Chinese style is embedded in modern Chinese. We don't often hear pure classical speech, but classical style phrases appear in writing a lot. Day to day conversation is made up of  'colloquial, literary, classical phrases and  slang'  
> **username_1**: @神秘德里克 1."請老師(垂鑒)"   2. "請老師(過目)"  3.請老師(看看). -- 垂鑒  is a formal term (to show respect), 過目 is a literary term (base on classical style) , 看看 is a colloquial term. The sentence: "天津是兵家必爭之地" is a mix of classical  and standard Chinese, and it is totally normal in modern Chinese writing and speech. But it is not considered 'formal form'  

---

### Answer by username_4 on 2018-11-28. Score: 0

It is the same, you can interchange the two.

> **Comments:**
> **username_1**: Yes, they mean the same, but they are for different styles (literary and colloquial), you cannot freely interchange them. When you replace  '必' with '一定' , you have to change the rest of the sentence sometimes. For example: "(必)無好果" =  "(一定)沒有好結果" ; you cannot just replace '必' with '一定' and write " 一定無好果"  

---

### Answer by username_5 on 2018-11-28. Score: -1

* 我必须去 I must go there (because of some reasons).
* 我一定去 I must go there (really want to, no matter what) .

They all mean you must go there sometime in the future.

However, 一定 is subjectively, 必 is objectively.


---

