let's
- let us
let's
You use let's when you are suggesting that you and someone else should do something. Let's is short for ‘let us’. It is followed by an infinitive without to.
Let's go outside.
Let's decide what we want.
The full form let us is used with this meaning only in formal English.
Let us postpone the matter.
If you are suggesting that you and someone else should not do something, you say let's not.
Let's not talk about that.
Let's not waste time.
‘let us’
When you are talking about you and someone else being allowed to do something, use let us.
They wouldn't let us leave.
His mum let us stay there for free.
You can use let us when you are making a request on behalf of yourself and someone else. In sentences like these, don't shorten let us to ‘let’s'.
Let us know what progress has been made.