Devoir vs avoir besoin de to express "to need to"

Look at these two sentences expressing the idea of "need": 

J'ai besoin d'aller faire les courses avant le dîner.
I need to go shopping before dinner.

Je dois aller faire les courses avant dîner.
I need to go shopping before dinner.

Devoir + [infinitif] primarily means must [do] / have to [do], but in some cases it can be used as need to [do].

See Conjugate devoir in Le Présent (present tense)

Avoir besoin de + [infinitif] always means need to [do], as it literally means "to have need of".

See Avoir besoin de = To need

 

As for expressing to need [something], it will always be avoir besoin de [quelque chose] :  

Elle a besoin d'aide.
She needs help.

Tu as besoin d'argent.
You need money.

ATTENTION: 

Devoir [quelque chose] has a completely different meaning = to owe [something].
It can never mean to need [something].

Tu dois de l'argent.
You owe money.

Patrick me doit une faveur.
Patrick owes me a favour.


Special cases
:
"needing to go to the toilet"

As stated above, you can use either avoir besoin de or devoir in that case, but you could also use avoir envie de (= to feel like) in this specific case : though it can sound a bit "whimsical", it's perfectly colloquial here!

Mon fils doit aller aux toilettes.
My son needs to go to the toilet.

Mon fils a besoin d'aller aux toilettes.
My son needs to go to the toilet.

Mon fils a envie d'aller aux toilettes.
My son needs to go to the toilet.

"needing to throw up"

Another weird case is how to say you feel nauseous, need to throw up. In French, the most colloquial expression there is to use once again avoir envie de (= to feel like), though no one really ever "feels like" vomiting!

Arrête la voiture ! J'ai envie de vomir !
Stop the car! I feel nauseous!

See also Avoir envie de = To feel like, want to

 

Learn more about these related French grammar topics

Examples and resources

Je dois aller faire les courses avant dîner.
I need to go shopping before dinner.


Patrick me doit une faveur.
Patrick owes me a favour.


J'ai besoin d'aller faire les courses avant le dîner.
I need to go shopping before dinner.


Arrête la voiture ! J'ai envie de vomir !
Stop the car! I feel nauseous!


Elle a besoin d'aide.
She needs help.


Mon fils a envie d'aller aux toilettes.
My son needs to go to the toilet.


Tu as besoin d'argent.
You need money.


Mon fils doit aller aux toilettes.
My son needs to go to the toilet.


Tu dois de l'argent.
You owe money.


Mon fils a besoin d'aller aux toilettes.
My son needs to go to the toilet.


Q&A

M

Kwiziq community member

23 November 2018

1 reply

Sorry again. The second sentence has only “dîner” without the “le”. Is there a reason for that?

Cécile

Kwiziq language super star

24 November 2018

24/11/18

Hi M

It is just a different way of saying the same thing:

Le dîner = dinner (noun)

Dîner = to have dinner (verb)

Hope this helps!

M

Kwiziq community member

23 November 2018

1 reply

Sorry was not finished.

Cécile

Kwiziq language super star

24 November 2018

24/11/18

answered...

M

Kwiziq community member

23 November 2018

1 reply

In the first example of the lesson, the sentence ends with “ le dîner”

Cécile

Kwiziq language super star

24 November 2018

24/11/18

answered...

William

Kwiziq community member

19 August 2018

2 replies

Is "avoir à" a possible alternative to "devoir"

Is avoir à a possible alternative to devoir?

Can avoir à ever be used instead of devoir? For example j'ai à vous remercier instead of je dois vous remercier.

Chris

Kwiziq community member

19 August 2018

19/08/18

I have heard "avaoir à" used in some specific context loke:

Tu n'as qu'à ranger ta chambre. -- You only have to clean up your room. 

 But I found a more comprehensive discussion here: https://www.reddit.com/r/French/comments/1urs43/avoir_à_vs_devoir/

Cécile

Kwiziq language super star

21 August 2018

21/08/18

Hi William,

As the lesson points out 'devoir' can be both 'to have to' or 'to need to' something .

'Avoir à' is mostly used to indicate an idea of need rather than must as in :

Tu n'as pas à t'excuser = You don't need to apologise (in other words - it was not your fault)

Tu n'as pas à faire ça You don't need to do that ( or even: there's no need for you to do that

J'ai à faire = I have things to do (there are things I need to do

so it may be best to use 'devoir' or 'falloir' to convey the idea of 'must'.

Hope this helps!

 

John

Kwiziq community member

30 May 2018

2 replies

Devoir

We are told that devoir can sometimes mean 'to need to [do]' yet only one example is given and no further explanation. In the example devoir is followed by a verb in the infinitive. Is that how devoir can be used?

Cécile

Kwiziq language super star

31 May 2018

31/05/18

Hi John,

This is quite subtle and it is when 'must' equals an imperative need to do something, rather than an obligation as the following examples will illustrate:

Je dois aller chez ma mère ce matin, elle ne va pas bien.

Je dois aller aux toilettes.

Je dois passer à la banque, je n'ai plus d'argent.

You would use 'devoir' rather than 'avoir besoin de' and as you have noticed it is followed by another verb in the infinitive.

Hope this helps!

John

Kwiziq community member

1 June 2018

1/06/18

Merci Cécile. Maintenant je comprends.

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