Translating “could”, “would” and “should” can sometimes be confusing because where we use modal verbs in English, the French use the conditional mood. However, the conjugations for the conditional mood translate to “would”, but they can also be used to say “could” and “should” with the conditional conjugations of devoir and pouvoir, which are used in much the same way as our modal verbs.
Using the conditional mood for would
The conditional mood generally translates to “would”, so if you want to say that you would do something simply use the conditional conjugation. As this is conditional, you will often find this in “si” clauses, but may also be used when the the conditional aspect is implicit:
Je voudrais une bière, s’il vous plaît – I would like a beer please.
On mangerait ici si l’on était riche – We would eat here if we were rich.
Il irait, mais il s’occupe des enfants – He would go but he is looking after the children.
Conditional Could with Pouvoir
To say “could” as a conditional – I could do something if something else were to happen – you use the conditional conjugation of the verb pouvoir (“to be able to”) followed by the infinitive of the verb of the thing that you could do, you may also think about it as “I would be able to”:
Je pourrais écrire une chanson sur tes yeux – I could write a song about your eyes
On pourrait prendre les escaliers – We could take the stairs.
Nous pourrions manger le dîner dans le salon – We could eat diner in the living room.
Ils pourraient faire plus pour aider leurs parents – They could do more to help their parents.
Je pourrais manger un cheval entre deux matelas – I could eat a horse between two mattresses.
Saying Should with Devoir
Firstly, “should” in this context is not a conditional, but it does require the French conditional conjugation of devoir (“to have to”) followed by the infinitive:
Je devrais être travailler – I should be working.
Tu devrais te lever – You should get up.
Ils devraient aider leurs parents – They should help their parents.
Nous devrions manger quelque chose – We should eat something.