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Can I Run This on My Generator?

Compare the AC devices you want to run at the same time with your generator’s running and starting watt ratings. Enter both ratings from the generator manual for your expected operating conditions, along with each device’s running and startup watts. The results show whether each load scenario is below, at, or above the ratings you enter.

Not sure what to enter? Read the step-by-step guide.

Your inputs

Your generator ratings

Use the generator’s continuous AC output rating in watts for the fuel type and operating conditions you expect. Do not use its starting or maximum rating.

Use the starting watt rating for the same generator, fuel type, and operating conditions. Check how long the generator can sustain this output.

Devices you want to run

AC device 1

Startup power is the device's total power draw while starting, not extra watts to add to its running power. If the device has no startup surge, enter its running watts in both fields.

Include all AC devices supplied by this generator at the same time, including a battery charger if it will be running. Startup watts are each device’s total power draw while starting. No appliance wattages are assumed.

Generator comparison

How your loads compare

Compared with the generator watt ratings you entered.

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While devices are running

Compared with the running rating.

One device starts at a time

Compared with the starting rating.

All devices start together

Compared with the starting rating.

Enter your generator ratings and the AC loads you want to run together.

This comparison does not confirm that your setup will operate safely or correctly. Check startup duration, voltage and frequency, VA/current limits, receptacle and circuit limits, derating, and motor-starting requirements in the generator manual. It does not assess wiring, transfer equipment, fuel use, or exhaust safety.

Edit your inputs
See calculation details, assumptions and sources

The Generator Size Calculator method gives three AC load values: continuous W = sum of quantity × running W; peak with one device starting (W) = continuous W + largest (startup W − running W); and peak with all devices starting together (W) = sum of quantity × startup W. A device’s startup watts are its total power draw while starting, not an extra amount.

Compare continuous load with the generator’s running W rating. Compare each startup scenario with its starting W rating. The displayed difference is entered rating − required W. A positive difference means the load is below the entered watt rating. A negative difference means the load exceeds the rating. Zero means the load is exactly at the limit. For example, a 1,475 W running load, a 2,675 W peak with one device starting, and a 3,175 W peak with all devices starting together compared with 2,000 W running / 3,000 W starting ratings give differences of +525 W, +325 W, and −175 W respectively.

Select the startup scenario that could actually happen. These W ratings alone do not show whether the peak can last long enough or whether voltage, frequency, receptacle current and power factor are compatible. Use actual AC input watts for appliances. Do not treat VA or DC battery draw as the same value. No automatic surge multiplier or safety margin is added.

References: Generac portable generator owner’s manual explains simultaneous running loads and motor startup demand; Champion’s explanation of running and starting W notes that a peak rating lasts only briefly. See the site methodology.