We have rented a house, the landlords would not do a lease we want to move now. How much notice do we legally have to give them.

ANY question on law needs to include your general locale as laws vary by area.

Generally its 30 days. But it could be a calendar month or less.

On average its 30 days minimum... usually set to end at the last day of the month (basically one full calender month) keeps everyone happy. And a glowing reference from your last landlord is nice to have. And as was mentioned... location is important. There are a handful of places in the USA that don't follow the norm, and if you are elsewhere. It may be completely different.

I agree with both gentlemen who answered. Please tell us where you are and how long you have lived in this unit.