Worksheet
Select the appliances you want to run during a power outage and see your running watt total, peak starting watt load, and a recommended minimum generator size — with a transparent breakdown of how the recommendation was calculated.
Add a custom appliance
Check your appliance nameplate or owner's manual for wattage values.
3 appliances selected
Load breakdown
Residential standby models that meet your calculated minimum.
Final selection also depends on transfer switch capacity and planned future loads.
Wattage figures are estimates based on typical appliance ratings. Actual values vary by brand, model, and age. A licensed electrician performs a formal load calculation to determine final generator sizing.
Powers essential circuits — refrigerator, LED lighting, sump pump, phone charging, and small electronics.
Planning examples — not a guarantee.
Use these tools in sequence for a complete picture.
Add up the running watts of all appliances you want to power, then add the starting surge of the single largest motor (not all motors — only one starts at a time). Apply a 25% safety buffer to that peak total and round up to the next standard generator size. This worksheet performs that calculation automatically as you select appliances.
Motors — refrigerators, air conditioners, sump pumps, and well pumps — need 2–4× their normal running wattage for a fraction of a second when they start. A generator must handle this inrush current without stalling. Always size based on starting (surge) watts for any appliance with a motor.
Yes, but central air conditioning is one of the largest loads in a home. A 3-ton AC unit typically needs 3,500 W to run and up to 7,000 W to start. You'll need a generator of at least 10–14 kW to run AC alongside other essentials. Check your unit's nameplate for exact values.
A whole-home standby generator typically ranges from 20–36 kW for most single-family homes. The exact size depends on your appliances, HVAC system size, and whether you have electric or gas appliances. Use this worksheet with your specific appliance list to get a personalized estimate.
Yes. Whole-house generator installation requires a licensed electrician to install the automatic transfer switch, connect to the electrical panel, and pass local inspections. Most areas also require permits. A professional also performs the formal load calculation that determines the final generator size.
Safety headroom (typically 20–25%) is extra capacity added above the calculated peak load. Generators run more efficiently and last longer when not operating at 100% of their nameplate rating. Headroom also accommodates small load spikes and any appliances you might add in the future.
