Portable Generator Running Watts by Appliance: Running & Starting Chart

Add the running watts of the appliances you expect to use together, then check the extra demand when a motor starts. A portable generator must support both operating conditions—not just a total based on appliance running watts. The chart below provides manufacturer reference estimates for building an initial load list; your appliance’s electrical input and startup requirements take precedence.

Appliance Running and Starting Watts

Find the appliance type and size closest to yours, then record its approximate running and starting demand. These figures come from the home and recreational sections of Honda’s generator wattage estimation guide, a U.S.-market reference chart rather than specifications for identified appliance models. Honda does not state a publication date or revision number on that page; each row records that limitation and the date consulted.

All power figures are in watts (W). “Starting watts” means the approximate total demand of that appliance during startup, not an additional amount to add to its own running watts.

Source for all appliance values: Honda’s wattage estimation guide. The ranges are reference estimates, not guaranteed limits for every appliance in that category. Where starting and running values are equal, Honda lists no additional starting allowance for that example; this does not establish that every comparable product has zero inrush.

Read the Appliance Rating Correctly

Use input power, not useful output. For example, Honda lists approximately 1,500 W of electrical demand for a microwave with a 1,000 W cooking rating. Likewise, the horsepower and cooling-capacity descriptions in the chart identify equipment categories; use the corresponding wattage estimate only until you obtain the actual appliance data.

Keep the furnace-fan entry separate from electric heating loads. Honda’s entry specifically describes a gas- or oil-furnace fan, not a complete electric furnace or heat-pump system.

How to Use the Chart

List only the appliances expected to operate together. Add their running watts, then examine each credible motor-starting event with the other operating loads still connected. Honda’s power-management guidance recommends starting high-demand appliances at different times rather than simply adding every appliance’s starting wattage.

Worked Example: Refrigerator, Sump Pump, and Coffee Maker

Assume the following loads from the chart:

• Refrigerator: 192 W running, using the upper end of Honda’s range; 1,200 W total during startup.
• Sump pump, 1/3 hp: 800 W running; 1,300 W total during startup.
• Coffee maker, 4-cup: 600 W operating demand.

These are reference inputs, not measurements of a particular installation.

With all three operating, the estimated running load is:

[
192 + 800 + 600 = 1{,}592\ \text{W}
]

If the refrigerator starts while the pump and coffee maker are operating:

[
1{,}200 + 800 + 600 = 2{,}600\ \text{W}
]

If the pump starts while the refrigerator and coffee maker are operating:

[
1{,}300 + 192 + 600 = 2{,}092\ \text{W}
]

For this assumed sequence, the preliminary checks are therefore 1,592 W running and a highest single-start event of 2,600 W. Do not calculate the refrigerator event as (1{,}592 + 1{,}200): that would count its 192 W running demand twice.

Notice that the pump has the higher individual starting figure, but the refrigerator produces the larger combined event. What matters is each appliance’s startup demand together with the other loads operating at that moment.

These results assume the refrigerator and pump do not start simultaneously. Automatic controls can restart either appliance without warning, so an initial manual startup sequence does not establish that later starts will remain separated.

What the Wattage Total Does Not Establish

The chart produces a preliminary load estimate, not confirmation that a particular portable generator will start and run the equipment.

Before relying on a generator–appliance combination:

• Replace chart estimates with the actual model’s electrical input and documented startup information wherever available.
• Check the generator’s rated running output separately from its advertised starting or maximum output.
• Confirm appliance voltage and frequency requirements, available receptacles, and individual outlet or circuit limits.
• For motor loads, check the generator manufacturer’s application guidance rather than treating a wattage total alone as proof of acceptable starting performance.

Do not mix figures from different reference examples without identifying the change. Honda’s separate generator power-management example uses different refrigerator and furnace starting figures from its appliance estimation chart. The calculations above consistently use the chart linked beside the table.

For appliances connected through building wiring, have a qualified electrician determine the connection arrangement and applicable local requirements; a wattage table cannot establish installation compliance. Portable-generator operation also requires carbon-monoxide precautions: CDC guidance says never operate a generator inside a home or garage, even with doors open, and to operate it outdoors more than 20 feet from windows, doors, and vents, with battery-powered or battery-backup CO detection in the home.