You need a Manual J (or an equivalent load calculation), not a “2,000 square feet is X tons” answer. Rules of thumb that divide floor area by a number of square feet per ton are common in sales conversations and are not a design method. Two 2,000-square-foot houses, one a tight recent build in a mild climate and one a leaky ranch in a cold climate with a lot of glass, can have very different loads. Oversizing can hurt humidity control and cycling; undersizing, especially for a heat pump that must also heat at design temperature, leaves the house on backup heat or uncomfortable.
This is the whole-house version of the mini-split sizing pages, and the same honesty applies. This site will not publish a fake precise sizing calculator or a “typical 3-ton” claim. What you can do before the contractor arrives is collect insulation levels, window types, plans or measurements, and the local design temperature, and ask to see the load report — heating and cooling — with the outdoor-unit capacity at that heating design temperature, not only the nominal tonnage on the brochure.
If the real questions are operating cost or panel capacity, those have tools: the operating-cost calculator and the panel calculator, plus the backup-strips page if the quote includes resistance heat.
This is not a permit calculation, a utility approval, or a substitute for a licensed electrician, HVAC contractor, or the authority having jurisdiction. Panel Headroom is an independent educational site. It is not a utility, a certification body, or a contractor. Electrical and generator work that is done incorrectly can cause fire, shock, or carbon monoxide poisoning. Use the adopted electrical code and manufacturer instructions; pull permits where required.