Choosing between c'est and il est to say it is

Both c'est and il est can mean it is... (or it's...) when it doesn't refer to anything very specific. One difficulty that this leaves is: when to use c'est and when to use il est?

The rest of this page looks at the choice between il est and c'est in more detail, but as a rule of thumb:

the phrase il est is generally used in impersonal constructions where it is followed by an adjective plus a clause (see below);
the phrase il est is also used with time expressions;
otherwise, the phrase c'est is generally used, and in general the ce refers to something, although generally something non-specific;
in informal speech, impersonal il est is frequently replaced with c'est.

Use of impersonal il est

As mentioned above, il est is used when:

the il is impersonal— in other words doesn't "refer to anything as such";
il est is followed by an adjective;
the adjective is followed by a clause (a phrase introduced by que "that..." or de "to...").

In practice, this means sentences such as this:

Il est difficile d'apprendre une langue étrangère
It is difficult to learn a foreign language
Il n'est pas facile de trouver un emploi en France
It's not easy to find a job in France
Il est impossible de savoir si...
It is impossible to know whether...
Il est probable qu'il fera beau demain
It's likely that it'll be nice weather tomorrow

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Use of c'est instead of il est in informal usage

In informal usage, it is common to use c'est instead of il est in sentences such as those above. So for example, the following would be completely normal in everyday speech:

C'est difficile d'apprendre une langue étrangère
C'est pas facile de trouver un emploi en France

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Use of il est in time expressions

Note that when stating the time, even in informal speech, il est is used:

Il est trois heures.
It's three o'clock.
Il est tard.
It's late.

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This means there's generally a difference in meaning between Il est trois heures and C'est trois heures. If you say c'est trois heures, this means it's three hours (as in "it's a three-hour journey", "it's a three-hour period of time" etc), for example:

Paris-Bordeaux, c'est trois heures.
Paris to Bordeaux is three hours.

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Other uses of c'est to mean "it is"

Most other cases where it doesn't refer to a specific object, it is or it's is generally translated with c'est. Note that this includes cases where it might refer to a general idea or a general type of object/item, just not to a specific one:

Je ne bois pas de café— c'est mauvais pour la santé.
I don't drink coffee— it's bad for your health.
Je ne parle pas italien. C'est trop difficile.
I don't speak Italian. It's too difficult.

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French grammar index
French-English dictionary
English-French dictionary