When would I use the gerund over the Al + infinitive construction?

Question

Is this construction interchangeable with Al+infinitive or is there a nuance where I would choose one over the other?

Silvia Piriz · Accepted Answer

Hola Devin P.
Good question! Both the gerund (-ando / -iendo) and the al + infinitive construction can be used to express the idea of “while / upon doing something”, but they are not always fully interchangeable.
The gerund is the more common choice when you want to describe two actions happening at the same time.
For example:
Me corté el dedo cocinando (“I cut my finger while cooking”).
Here, the gerund highlights the background action that was in progress.
The al + infinitive structure is more formal and often used when you want to emphasise the moment of starting an action.
For example:
Al entrar en la sala, todos se levantaron. (“When/On entering the room, everyone stood up”).
It often carries a slightly more literary or precise tone than the plain gerund.
In many cases, you could use either without changing the meaning too much, but the nuance is that the gerund stresses the simultaneous action, while al + infinitive stresses the trigger or initial moment of the action.
Hasta pronto
Silvia