Calculating Your Actual Wattage Needs
3. Doing the Math
Alright, time to put on your thinking cap and do a little detective work! Grab a notebook (or a spreadsheet, if you're feeling fancy) and start making a list of every appliance and electronic device in your home. For each item, jot down its wattage. You can usually find this information on a sticker on the appliance itself or in its user manual. If it only lists the amperage (amps), you can calculate the wattage by multiplying the amps by the voltage (usually 120 volts in the US). Wattage = Amps x Volts.
Now, this is where it gets a little more interesting. You need to estimate how many hours per day each appliance typically runs. A refrigerator, for example, runs almost constantly, but only actually draws power when the compressor is running (which might be for, say, 8 hours a day). A light bulb might only be on for a few hours each evening. A television might be on for several hours on weekends but barely at all during the week. Be realistic. Don't overestimate, but also don't underestimate. It's all about getting a decent ballpark figure.
Once you have the wattage and the daily usage hours for each appliance, multiply them together. This will give you the total watt-hours per day for that appliance. Then, divide that number by 1000 to get kilowatt-hours (kWh) per day. Add up the kWh per day for all your appliances, and you'll have a rough estimate of your total daily energy consumption. This is the magic number that will tell you if 4000 watts is in the realm of possibility or completely unrealistic.
Don't forget about the "phantom load" or "vampire load"—the energy used by devices even when they're turned off but still plugged in. Things like phone chargers, televisions, and coffee makers often draw a small amount of power even when they're not actively being used. It might seem insignificant, but it can add up over time. Consider using power strips to easily cut off power to these devices when you're not using them.
