A full NEC load calculation on the service you already have. A couple of minutes, and nothing needs opening. If you are adding a heat pump in the same year, check that too, because the answer is not the same as adding either one on its own.
Answer what you know and skip what you don't. Where something is missing we say so, and say what would settle it, rather than guessing and hoping.
Which calculation this is. The existing dwelling method, NEC Article 220.83. It answers one question: whether the service you already have carries what you are adding. It is not a design for a new service, and it will not tell you what size to install if the answer comes back short. The result names the exact table used, which depends on the code edition in force and on whether heating is part of the job.
This is a planning estimate from Hanco Electric, based on what you entered and on the code edition and local amendments for the city selected. It is not a design, not a permit submittal, and not a substitute for a licensed electrician evaluating your installation on site. The authority having jurisdiction has the final say on any load calculation.