How to Size a Generator for Your Home: Choose with Confidence

Write down the appliances and systems you cannot live without—refrigerator, sump pump, lights, Wi‑Fi, furnace blower, medical devices. Note each item’s running watts from labels or manuals, then confirm how often they operate. Share your must‑run list in the comments so others can compare and learn.

Do the Math: Total Wattage and Realistic Simultaneous Loads

Group devices that will be on at the same time—lights, Wi‑Fi, fridge, furnace blower, and a few outlets. Add their running wattage to form a base load. Then confirm whether any large motor loads overlap. Post your draft calculation below and we’ll sanity‑check it together.

Do the Math: Total Wattage and Realistic Simultaneous Loads

For circuits with motors, add the highest likely starting wattage to your base. If multiple motors can start together, plan for the worst case. Soft‑start kits can reduce inrush dramatically, letting you choose a smaller generator. Curious about soft starts for your HVAC? Ask and we’ll explain options.

Fuel, Environment, and Performance That Affect Sizing

Natural gas offers convenience but can deliver slightly less power than propane per engine rating. Propane stores well and starts reliably in the cold. Diesel excels for heavy-duty loads but needs careful fuel maintenance. Share your fuel access and climate, and we’ll help align the generator size with real conditions.

Transfer Strategy That Shapes Generator Size

Whole‑House vs. Essential Circuits

Whole‑house transfers demand larger generators because any circuit might run. An essential‑circuits subpanel feeds only critical loads, often reducing size dramatically. Decide what comfort means during outages—then size accordingly. What would you include in your essential panel? Share and compare with readers.

Manual vs. Automatic Transfer Switches

Automatic switches restore power quickly and safely, ideal when you’re away. Manual options cost less but require presence and attention. Either way, mapping circuits thoughtfully can cut peak demand. Interested in a sample subpanel layout? Comment and we’ll send an example for typical homes.

Load‑Shedding Modules for Big Appliances

Smart modules temporarily pause heavy loads—like electric water heaters or second HVAC compressors—when demand peaks. This keeps a smaller generator from tripping while maintaining comfort. Ask about compatible load‑shedding gear for your equipment and how it can reshape your sizing plan.

Technology Choices That Influence Sizing

Inverter generators deliver low total harmonic distortion, kinder to electronics, and they throttle to match demand. For smaller essential loads, they’re quiet and fuel‑efficient, often allowing a more modest size. Are your priorities quiet operation and laptops? Tell us and we’ll weigh inverter pros and cons.

Technology Choices That Influence Sizing

A soft‑starter on central air can drop starting current dramatically, helping a 9 kW generator act like a bigger unit during startup. Many readers report success through heatwaves. Wondering if your compressor is a candidate? Leave the model number and we’ll suggest a path to verify compatibility.

Long cable runs increase voltage drop, causing motors to struggle and surge higher. Keep generators reasonably close, sized conductors correctly, and plan for 120/240‑volt loads. Ask us to estimate wire gauge and distance impacts so your chosen size delivers full, reliable power at the panel.

Placement, Safety, and Installation Realities

Real‑World Sizing Stories and Takeaways

Cozy Cabin with Essentials Only

A 600‑square‑foot lakeside cabin ran lights, Wi‑Fi, a compact fridge, and a small well pump with a 3200‑watt inverter generator. Soft‑starts kept the pump civilized. They skipped electric heat and managed cooking carefully. What essentials would your weekend place need? Share your cabin wishlist.

Suburban Home on an Essentials Subpanel

A 1,800‑square‑foot home with gas heat chose a 7.5–9 kW range by moving fridge, furnace blower, sump pump, lighting, and office circuits to a subpanel. A manual transfer kept costs tame, and scheduling avoided microwave overlaps. Could this approach fit your home? Post your circuit list for feedback.