No engineering degree required. A plain-English chart, real appliance wattages, and a tap-to-check calculator that does the same math we use on real quotes.
Start here. Most homes land in one of these five rows.
| If You Want to Run... | What That Covers | Good to Know | Generator Size |
|---|---|---|---|
| Essentials only | Fridge, lights, sump pump, phone charging, gas furnace fan | Small home or budget backup | 10 to 14 kW |
| Small home | Up to about 1,800 sq ft, one A/C, gas appliances | Most starter homes | 14 to 18 kW |
| Typical home | 2,000 to 3,000 sq ft, one central A/C, mixed appliances | The most common quote we write | 22 to 26 kW |
| Large home | 3,000 to 4,500 sq ft, two HVAC systems or electric heat | Two A/C units change the math | 26 to 32 kW |
| Estate / all-electric | 4,500+ sq ft, dual HVAC, pool, EV charger, shop | Liquid-cooled territory | 36 to 48 kW |
Check the boxes. We add the running watts, the biggest startup surge, and 25% safety headroom, the same math we use on real quotes.
Sizes are planning estimates. Nameplate watts vary by model and altitude cuts output about 3% per 1,000 ft, so before you buy, let us confirm it free from your electric bill.
The gold column is the one that matters: starting (surge) watts is what actually sizes a generator. Motors spike 2 to 3x their running draw for a few seconds at startup.
| Appliance | Running Watts | Starting (Surge) Watts |
|---|---|---|
| Central A/C (3 ton) | 3,500W | 9,800W |
| Central A/C (4 ton) | 4,500W | 12,500W |
| Electric furnace | 10,000W | 10,000W |
| Gas furnace fan | 800W | 2,350W |
| Heat pump | 4,700W | 10,500W |
| Well pump (1 HP) | 2,000W | 4,000W |
| Sump pump | 800W | 1,300W |
| Refrigerator/freezer | 700W | 2,200W |
| Electric water heater | 4,500W | 4,500W |
| Electric range (2 burners) | 5,000W | 5,000W |
| Microwave | 1,200W | 1,200W |
| Dishwasher | 1,500W | 1,500W |
| Washing machine | 1,150W | 2,250W |
| Electric dryer | 5,400W | 6,750W |
| Lights + outlets (whole home) | 1,500W | 1,500W |
| TV + internet + computers | 600W | 600W |
| EV charger (Level 2) | 7,200W | 7,200W |
| Pool pump | 1,100W | 2,200W |
| Medical equipment (CPAP/O2) | 500W | 500W |
| Window A/C unit | 1,200W | 3,600W |
For a quick answer: 14 to 18kW for a small home running one A/C, 22 to 26kW for a typical 2,000 to 3,000 sq ft home (our most common quote), and 26 to 32kW once you have two HVAC systems or electric heat. Starting (surge) watts decide the size, not running watts: a 4-ton A/C runs at about 4,500W but surges past 12,000W at startup. Use the checklist calculator on this page, then text POWER to 816-785-1268 and we'll confirm it free from your electric bill.
Running watts is what an appliance uses continuously. Starting (surge) watts is the spike motors need for 1 to 3 seconds at startup, often 2 to 3 times higher. A/C compressors, well pumps, and sump pumps are the big surgers. Generators must be sized for the largest surge plus everything else running, which is why square footage alone gets it wrong.
Yes. Air-cooled engines lose about 3% of output per 1,000 ft of elevation. In Albuquerque (5,300 ft) a 22kW unit delivers roughly 18.5kW; in Santa Fe (7,200 ft) about 17.4kW. That's why every New Mexico quote we write is elevation-corrected: it's our specialty.
Oversizing wastes money twice: higher purchase price and worse fuel efficiency at light loads (and air-cooled units running far below capacity can wet-stack). The right answer is sizing to your real loads with about 25% headroom, which is exactly what our free sizing does.
Three fields, then a real person calls or texts you back, usually the same business day. Free load sizing, factory-direct pricing, no commissions.
An undersized generator trips under load; an oversized one wastes your money. Our free sizing from your electric bill nails it, and quotes all eight brands at that size.
Or text POWER to 816-785-1268. Real reply from a real person, usually within the hour.
