The load list is the document the whole installation follows from, and it is not difficult to build.
The columns
Appliance. Everything that might be wanted during an outage.
Volts. 120 or 240.
Running watts, from the nameplate. Where the nameplate gives amps, multiply by the voltage.
Starting watts, from the nameplate's LRA where given, or estimated as a multiple of running watts for induction motors.
Essential, useful or unnecessary.
Sheddable, meaning it can be dropped when the generator is busy.
Where the numbers come from
Nameplates, which are on the appliance — on a plate at the back of a refrigerator, inside the door of a washer, on the outdoor unit of an air conditioner, on the well pump's control box.
Manuals, where the plate is unreachable.
Manufacturer websites, by model number.
Do not use general tables where a nameplate is available. The spread within a category is wide.
Deciding what runs together
This is the judgement, and it is where the household's knowledge beats any table.
Walk through a realistic winter evening and a realistic summer afternoon during an outage. What is actually on at the same moment?
The furnace, the refrigerator, the freezer, some lighting, the internet equipment, and one of the pumps is a typical simultaneous set — and it is a much smaller number than the total of everything on the list.
The two totals
Total running watts of everything on simultaneously.
Plus the largest single starting surge, since two large motors starting in the same instant is a coincidence rather than a design condition.
That sum is the peak the generator must survive.
Then apply the reductions
Soft starters on air conditioning compressors, which cut the largest surge substantially.
Shedding on the water heater, the air conditioning and the range, which removes them from the simultaneous total.
Locking out electric resistance backup heat, or allowing one stage of it.
Each of these is cheaper than a generator size step, and together they frequently bring a large house within a mid-sized unit.
Then apply the derating
The generator's output at your elevation and expected summer temperature, from the manufacturer's tables, is lower than its nameplate.
Compare the peak against that derated figure, not against the nameplate, and leave ten to twenty percent margin for loads added over the years.
What the list is for
It goes to every installer quoting the job, so the quotes are comparable.
It determines the generator size, the transfer arrangement, the shedding priority and whether a soft starter is needed.
And it is the document that reveals, before any money is spent, whether the household actually wants whole-house backup or whether an essential-circuit installation covers what matters — which is usually a difference of one or two generator sizes.
Keep it
Loads change. A freezer in the garage, a vehicle charger, a heat pump water heater, a hot tub.
Revisiting the list every few years is how a household notices that the generator installed for the house of ten years ago is no longer sized for the house of today.
The loads people leave off
The internet equipment, which is how a household finds out anything.
The septic or sewage ejector pump, which is out of sight.
The garage door opener, in a house whose only vehicle exit is powered.
A second refrigerator or a chest freezer in the garage or basement.
Medical equipment, which belongs at the top of the list and is sometimes not thought of as an appliance.
Walking the house with the panel directory catches all of these, and the exercise usually turns up at least one circuit nobody could identify.
Power factor
Nameplate watts and volt-amps are not the same for motor loads, and a generator is rated at a power factor of 0.8.
For a household list this rarely changes a decision, and it is worth knowing when a total in watts is compared against a generator rating in kW that assumed otherwise. Where the sizing is close, ask the installer to check it in volt-amps.