WHat are the difference between “I cooked dinner in 1 hour” & “I cooked dinner for 1 hour”?

Question

WHat are the difference between "I cooked dinner in 1 hour" & "I cooked dinner for 1 hour"?

The dictionary says:

We use in to say how long it takes someone to do something:

He was such a clever musician. He could learn a song in about five minutes.

The dictionary also says

We use for with a period of time to refer to duration (how long something lasts):

There’s a lovely open-air pool near us. We usually go there for a couple of hours in the evenings when it’s warm enough.

SO, "I cooked dinner in 1 hour" = it took me 1 hour to cook dinner

& "I cooked dinner for 1 hour" = cooking dinner lasted 1 hour

When to use "I cooked dinner in 1 hour" & when to use "I cooked dinner for 1 hour"?

Answer 1

I cooked the dinner in two hours.

Implies the dinner was ready after 2 hours.

I cooked the dinner for two hours.

Implies for 2 hours I was busy cooking the dinner.
for shows a length of time whereas in expresses that something was complete after a certain time.