I bought a house with a 100 amp service but it only has 16 slots and 6 are filled with 220 volt breakers stove is on 1 and the rest is crowded on to other 7 breakers. I am finishing my basement and putting up a new garage and I want to install a sub panel so I can run 2 more 220 lines and ad outlets to the basement and basement. So what size sub panel should I use.

Bob,

I have requested that your e-mail address be removed from your posting. It not wise to post direct contact information into an open forum.

As to your question, it is not as simple as just sticking a secondary panelboard onto the system. You really need a "Load Calculation" completed to see if your current service level will support an additional load.

In this instance, please consider that it might be more prudent to contact your POCO and see if they can increase your service to 200 amp. Then replace the existing panelboard with a listed 200 amp panel with the number of slots you need, plus at least two.

20, 30 and 40 slot 200 amp some of the available panels can be expanded as far as 80 slots through the use of trimline circuit breakers. Loadcenters are available from Lowe's, Home Depot and probably just about any hardware store.

I would not use a subpanel, you need to upgrade to at least a 150 Amp service, in my opinion.

Agree with Don... first we have not been given enough information to make any judgements, i.e. what size is the house? Do you have gas or electric cooking? Gas or electric heat? Any other substantial electrical loads?
Then a bigger panel or service upgrade can be recommended...