What Size Generator Do You Actually Need? A Real-World Power Budget

Quick verdict: For most homeowners who want to keep the fridge, sump pump, a window AC, lights, and devices running during an outage, a 5,000–7,500W portable generator covers it comfortably — the Westinghouse WGen7500 hits that sweet spot with dual-fuel flexibility and room to grow.

## What Can You Actually Run on a Generator? Here's the question nobody asks at the hardware store: not "how many watts is this generator?" but "how many watts do I actually need?" Most people answer the second question by guessing at the first. They grab a 3500W generator because it sounds like a lot, lose power during a nor'easter, and discover their well pump alone needs 2000W to start. The fridge never turns back on. The smarter move is to build your power budget first. Figure out what matters to you — what you'd be genuinely miserable without during a three-day outage — and then size backward. This guide gives you the numbers to do exactly that. --- ## The Real Wattage Chart: What Things Actually Draw Every generator spec sheet lists two numbers: running watts and starting watts (also called surge watts). This distinction matters enormously and it trips up almost everyone. Running watts is what the device needs to operate continuously. Starting watts (surge) is the spike of power the motor needs to get moving — it lasts less than a second, but your generator has to supply it. Electric motors (refrigerators, pumps, air conditioners) have starting wattages that are 2–3x their running wattage. If your generator can't supply the surge, the motor won't start — and trying repeatedly can damage both the generator and the appliance. Here's what the common household items actually draw:

Refrigerator: 150–400W running, 800–1,200W starting surge. This is the item most people correctly identify as essential. The running draw is modest; the startup surge is what bites you. An older, less efficient fridge can draw toward the high end of both ranges. Chest freezer: 100–200W running, 400–600W starting. More efficient than an upright. If you have a full chest freezer of food you don't want to lose, this belongs on your priority list. Microwave: 600–1,500W running (no meaningful surge — it doesn't have a motor). A basic 700W microwave draws about 700W. A 1,200W microwave draws about 1,200W. The label tells you directly. Coffee maker: 600–1,200W running. Drip coffee makers are straightforward resistive loads — no surge, just heat. During a three-day outage this stops being optional. Electric kettle: 1,200–1,500W running. Fast and efficient but a high draw. On a small generator, run it alone rather than simultaneously with other high-draw items.

Window AC unit (5,000 BTU): 500W running, 1,500W starting surge. A small bedroom unit. This is manageable on a mid-size generator if you're not running everything else at the same time. Window AC unit (10,000 BTU): 900W running, 2,700W starting surge. A larger room or open-plan space. That 2,700W surge is significant — it can be the biggest single demand spike in your power budget. Central air conditioning (3-ton system): 3,500W running, 10,000W+ starting surge. Unless you have a large standby generator, you're not running central AC on a portable. This is one of the honest truths about portable generators: they are not whole-house power solutions for most homes. If whole-house AC is the goal, a standby generator is the answer. Space heater: 750–1,500W running. Resistive heat, no surge. If you're in a cold climate and the generator is your heating backup, a 1,500W space heater will work fine but takes a meaningful chunk of your capacity. Gas furnace blower (electric fan on a gas furnace): 300–800W running, 800–1,600W starting. This is a frequently overlooked item that matters a lot in cold climates. You have a gas furnace — great, you don't need to power the burners. But the blower fan that circulates the heat is electric. Without generator power to the blower, the furnace won't run even if the gas is flowing. Add this to your power budget. Ceiling fan: 15–75W. Trivial. Run as many as you want.

Sump pump: 800–1,050W running, 1,300–2,150W starting. If you have a basement in a flood-prone area, this is the item that turns a manageable outage into a disaster if your generator can't handle it. The surge on a 1/2 HP sump pump can hit 2,150W — that single device will be the peak demand in most residential power budgets. Well pump (1/2 HP): 750–1,000W running, 2,000W starting. If you're on well water, no generator power means no water — toilets, drinking, everything. Well pumps are non-negotiable for rural households. Size your generator with the well pump surge in mind. Electric water heater: 4,000W running. Almost certainly skip this. Electric water heaters draw more than most portable generators can sustain and are a non-essential load during an outage. If you have a gas water heater, this is a non-issue.

LED bulb: 8–15W each. Six LED bulbs is 90W total. Essentially free from a generator capacity standpoint. Phone and tablet chargers: 5–25W each. Also essentially free. Laptop: 45–100W. Small load. Keep it on the list for accuracy but it won't drive your sizing decision. 50-inch TV: 80–150W. Reasonable entertainment during an outage without meaningful impact on capacity. Internet router and modem: 10–20W combined. Add this — having internet access during an outage is increasingly important, and it costs almost nothing in power.