Each condominium's Master Deed and Declaration of Trust is different, therefore the way the condo fees are set up are different. Many condo fees are based on square footage, however the fees could also be based on market value...for instance the location level of the condo in the building, whether or not it has outdoor space or parking. Sometimes utilities and parking are included in the fees but, often parking spaces are separate fees, especially if not every unit has parking.
When you find a condo you like, an attorney will be able to read the condo docs for you and let you know how the fees are determined.
If you are not presently contracted with a buyer's agent, please give me a call to discuss further.