First conditional

if + present tense | will + infinitive

The first conditional describes a probable future situation. If the condition is fulfilled, the action in the main clause is likely to happen:

If we don't leave soon, we will miss the train.
If you ask him, he will probably help you.

In this type of conditional, the present tenses in the if-clause usually refer to future time and their use is similar to that in future time clauses. Sometimes, however, a present tense in the if-clause can refer to present time:

If you are hungry, you'll find some sandwiches in the fridge.

Compare the zero and the first conditionals:

If I drink too much, I usually get a hangover the following day. (zero conditional to refer to a general situation; one action is always followed by another)

If I drink too much, I will get a hangover tomorrow. (first conditional to refer to one specific future situation)