How can I calculate the total electrical load for my home to avoid circuit overload?

Calculating a home's total electrical load involves summing the wattage of all connected appliances and lighting, then dividing by the system voltage, typically 240 volts in North American split-phase services. The NEC Article 220 provides a standard method: assign 3 volt-amperes per square foot for general lighting and receptacle loads, add 1,500 VA for each small-appliance branch circuit and laundry circuit, then apply a demand factor of 35% to the portion exceeding 3,000 VA. Fixed appliances like water heaters or air conditioners are added at 100% of their nameplate rating. The total computed load determines the minimum service capacity, commonly 100, 150, or 200 amperes, ensuring the main breaker and panelboard are adequately sized to prevent overheating and nuisance tripping.