The answer to 'what size electrical meter do I need' is that the size of the electrical meter you need will depend on the size of your home and the amount of electrical power it requires. Most residential homes will require a standard 200-amp electrical meter, which is capable of handling the electrical load for a typical single-family home.
The size of the meter is important because it needs to be able to handle the maximum electrical load your home will require. If you have a larger home with high-power electrical appliances or equipment, you may need a larger 400-amp or even 600-amp meter. It's best to consult with a licensed electrician to determine the appropriate meter size for your specific home and electrical needs.