Hiring an au pair is a great way to ensure your children grow up well and safely. Starting costs for a live-in nanny is average at $177 per week, or $785 per month. This is in addition to providing them with a room and food. A live-out nanny generally charges more, but room and board will not be required so the overall cost may end up being less. Au pair salaries may change depending on their performance, economic conditions, and local cost of living.