Difference Between Allow, Permit And Let

These words have similar meanings. Permit is more formal than allow.

Both allow and permit can be followed by object + infinitive.

An -ing form is used after allow / permit if there is no personal object.

Permit can be used in the passive form with it. Passive forms of allow cannot be used with it.

With adverb particles only allow is used.

Let is less formal than allow and permit. It is followed by an object + infinitive without to.

Passive structures with let are not usually possible.

Let can be used with adverb particles like in and out.