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Home Readiness — Guide
What Size Generator Do I Need for My House? (1,000–3,000 Sq Ft, Worked Out)
Short answer: Square footage is the wrong unit — generators do not power rooms, they power appliances. But size still brackets the answer: the essentials run about 1,650 watts in a typical 1,000 sq ft house and about 3,900 watts in a 3,000 sq ft one, with worst-minute starting peaks from roughly 2,600 to 5,600 watts. Most houses land in the 3,500–5,000 watt inverter band — all three picks below sit in it — and a well pump or a window air conditioner is what pushes a bigger house past it. The size table is next, three worked houses show the math, and the sizer near the end runs your house and your fuel.
Last updated: November 1, 2026
THE SHORT VERSION
Quietest pick
Westinghouse iGen4500
86/100 (8.6/10)
$849
3,700 running watts at a rated 52 dBA — the quiet one here. What it runs: fridge, furnace blower, sump pump, lights, and router together (about 1,900W if everything overlaps), up to 18 hours at quarter load on 3.4 gallons.
Gasoline or propane, so the grill tank is a second fuel supply. What it runs: the same essentials at 3,500 running watts on gas (3,150W on propane) — 14 hours at quarter load on gas, up to 21 hours on a 20 lb propane tank.
Lowest price here for the same 3,500 running watts, with a fuel shut-off that drains the carburetor for storage. What it runs: fridge, blower, sump, lights, and router — about 8.5 hours at half load on 2.2 gallons. Pull start only.
Square feet still give a usable first pass — a bigger house tends to add a second fridge, a bigger blower, a well pump. Here is the band each size lands in, worked from the load lists on this page. The 1,000, 2,000, and 2,500 sq ft rows are fully worked below; the 1,500 and 3,000 rows are the same load lists scaled, so treat them as planning numbers, not measurements.
House size
Typical running load
Worst-minute peak
Generator class
1,000 sq ft
~1,650W
~2,600W
3,500–5,000W inverter
1,500 sq ft
~1,900W
~3,100W
3,500–5,000W inverter
2,000 sq ft
~2,400W
~3,900W
4,500W inverter — top of the band
2,500 sq ft
~3,600W
~5,100W
5,500–7,500W, or shed the window AC
3,000 sq ft
~3,900W
~5,600W
7,500W class
Two loads break the pattern: a well pump (up to 2,000 starting watts on its own) and electric heat or central air, which no portable in this class runs. If either is on your list, size from the worked examples and the sizer below, not from this table.
Why square footage misleads
A 1,000 sq ft house and a 2,400 sq ft house can own the exact same refrigerator. The fridge does not know how big the house is, and neither does the furnace blower or the sump pump. What changes with house size is mostly air conditioning and electric heat — loads a portable generator usually leaves off anyway. So skip the square feet and add up the machines instead.
Here is our worked example: a 1,000 sq ft house with a basement and 200-amp service, gas furnace, city water, and the goal of keeping food cold, the basement dry, the house warm, and the phones charged.
Load
Running watts
Starting watts
Refrigerator
150
800
Furnace blower
700
1,400
Sump pump (1/3 hp)
800
1,300
LED lights, 6–8 bulbs
120
120
Router, modem, phone charging
40
40
TV
120
120
Add the running column and you get 1,930 watts — the unlikely minute when everything is on at once. Most of the outage, the real draw sits between 1,500 and 1,800 watts, because the fridge and sump cycle on and off. That fridge uses about 1,200 watt-hours a day on its own, which is why it anchors every plan on this site.
The number that picks your generator is the peak. Motors surge for a second or two when they start. If the furnace blower kicks on (1,400W starting) while the fridge, sump, lights, and router are already running (about 1,230W), you need roughly 2,600 watts in that moment. A well pump starting (up to 2,000W) or a window air conditioner pushes the worst minute toward 4,000 — so plan the peak there, not at the average. A generator with 3,500 running watts and 4,500 starting watts covers the list with headroom — and headroom matters, because a generator run flat-out all night is loud, thirsty, and short-lived.
One note for houses on a well: a 1/2 hp well pump adds roughly 1,000 running watts and up to 2,000 starting watts — the top of this band, and the load where staggering earns its keep. A window air conditioner is the other swing load, at 1,000–1,500 running watts.
A worked 2,000 sq ft house — well water and a basement
Same method, bigger house: two floors, a basement, gas furnace, and a private well — the load that changes everything, because the pump that makes your water is also the biggest motor you own.
Load
Running watts
Starting watts
Refrigerator
150
800
Chest freezer
120
700
Furnace blower
700
1,400
Well pump (1/2 hp)
1,000
2,000
Sump pump
800
1,300
LED lights
150
150
Router, modem, phone charging
40
40
TV
120
120
All-on, that is 3,080 watts; the real draw most of the outage is 2,200–2,600. The worst minute is the well pump starting — 2,000 watts of surge on top of roughly 1,840 already running — for a peak near 3,900 watts. The verdict: the same 4,500 starting-watt band covers this house, but it is the top of the band. The Westinghouse’s 3,700 running watts carry the most headroom of the three picks; on the Champion or the WEN (3,500 running), stagger the well pump against the sump pump and the freezer. The full math on the pump itself is in what size generator runs a well pump.
A worked 2,500 sq ft house — the one that outgrows the band
Add a second fridge, a 3/4 hp well pump, and a window air conditioner for the bedroom, and the honest answer changes: this house is past the three picks below, and pretending otherwise is how generators get returned.
Load
Running watts
Starting watts
Two refrigerators
300
1,600
Chest freezer
120
700
Furnace blower
800
1,600
Well pump (3/4 hp)
1,300
2,600
Sump pump
800
1,300
Window air conditioner
1,200
1,800
LED lights
180
180
Router, modem, phone charging
40
40
All-on is 4,740 watts, typical running is 3,400–3,900, and the worst minute — the well pump starting over a house already drawing hard — peaks near 5,100 watts. No 4,500 starting-watt machine covers that peak. The real options are a 5,500–7,500W dual-fuel machine, two inverters in parallel, or discipline: drop the window air conditioner and stagger the two refrigerators (start one, let it settle, start the other), which pulls the worst minute back inside the 4,500W band. If the cooling load is really a heat pump rather than a window unit, the heat-pump math is harsher still.
Generator size and fuel sizer
Pick a house size, pick a machine, pick how many hours a day it runs. The sizer checks the worst-minute peak against the machine’s starting watts and the typical load against its running watts, then works out the fuel: gallons an hour at your load, gallons a day, and how much to store for 3, 7, and 14 days. The Champion runs on either fuel — pick the one you would actually burn. Fuel figures are interpolated between each maker’s published runtime points. Champion publishes only a quarter-load point, so beyond it the sizer holds the quarter-load burn rate per watt-hour, which overstates burn at higher loads — plan on the high side. Nothing here is tested by us; it is arithmetic on the makers’ own numbers.
Covers it. Your worst-minute peak of about 3,900W fits inside 4,500 starting watts, and your typical load of about 2,400W sits at about 65% of its 3,700 running watts — a working load it can hold.
Fuel at that load: about 0.32 gallons an hour, 2.5 gallons of gasoline a day at 8 hours a day. Store 7.6 gallons for 3 days, 17.8 for 7 days, 35.5 for 14 days. That is about 0.7 refills a day from its 3.4-gallon tank.
Why this one: 3,700 running watts at a rated 52 dBA — the quiet one here. What it runs: fridge, furnace blower, sump pump, lights, and router together (about 1,900W if everything overlaps), up to 18 hours at quarter load on 3.4 gallons.
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Westinghouse iGen4500 — the quiet one
The iGen4500 makes 4,500 starting watts and 3,700 running watts, with a 3.4-gallon tank rated for up to 18 hours at quarter load. The headline number is the noise rating: 52 dBA, the lowest here by a wide margin — the difference between a generator you can talk over and one the whole street hears. It starts three ways — remote fob, push-button electric, recoil backup — with a TT-30R RV outlet and clean power under 3% THD.
Noise, in decibels
Lower is the one you can talk over — measured for these three machines on this page.
Champion 4,500W Dual Fuel
61 dBA
WEN 56450i
58 dBA
Westinghouse iGen4500
52 dBA
The owner sample is the largest here: from 8,044 owner ratings averaging 4.6 stars. Recurring complaints are narrow — oil changes are messy because there is no drain tube, so the unit gets tipped to pour, and a faulty-choke issue on earlier units shows up in older reviews, with Westinghouse sending a fix memo. At roughly 98 pounds, plan on two people or a ramp to load it.
One change since this review was first scored: Westinghouse’s own store now lists a successor, the iGen5000 (3,900 running watts, $1,099 list), in this model’s place. The iGen4500 is still sold by Amazon and other retailers, and its 8,044-rating owner record is the one scored here — the iGen5000 has no comparable record yet.
When/who: pick this one if the generator will sit close to the house, and you want to start it from indoors at 2 a.m. with the fob.
Champion 4,500W Dual Fuel Inverter (200988) — the flexible-fuel one
The Champion makes the same 4,500 starting watts, with 3,500 running watts on gasoline and 3,150 on propane. Dual fuel is the real feature: gasoline gives full output and up to 14 hours at quarter load from the 2.25-gallon tank, while a 20 lb propane tank trades a little power for up to 21 hours and fuel that does not go stale. Electric start, low-oil shut-off, under 3% THD, and 61 dBA at 23 feet — normal-conversation loud, noticeably more than the Westinghouse. About 97–103 pounds, with never-flat tires and a fold-down handle.
Quarter-load runtime, by fuel
A 20 lb propane tank trades a little power for hours more runtime — and fuel that does not go stale.
On a 20 lb propane tank
up to 21 hours
On gasoline — 2.25-gallon tank
up to 14 hours
The owner sample is solid: rated 4.7 stars based on over 1,400 customer reviews in the Amazon listing data we pulled. Sourced complaints are about the experience around the machine — review roundups note a fiddly start dial and long waits on support lines. We could not verify a current Amazon price on the day we checked, so no price is printed above; this model discounts often, so the listing is worth checking.
When/who: pick this one if you already keep propane on hand, or you do not trust stored gasoline to stay fresh between storms.
Gasoline or propane, so the grill tank is a second fuel supply: the same essentials at 3,500 running watts on gas — 14 hours at quarter load on gas, up to 21 hours on a 20 lb propane tank.
The WEN matches the Champion on paper: 4,500 starting watts, 3,500 running watts, 212cc engine, RV-ready TT-30R outlet, digital display. It is quieter than the Champion at 58 dBA at quarter load, and its fuel shut-off — which burns the last fuel out of the carburetor before shutdown — is a genuinely useful storage feature on a machine that may sit for months. The trade-offs are plain: pull start only, and a smaller 2.2-gallon tank good for about 8.5 hours at half load. It weighs 99.2 pounds.
The evidence here is the thinnest of the three, and the score says so: from 17 owner ratings averaging 4.4 stars on the Amazon listing data we could verify — a small sample, so treat it as a rough signal, not a verdict. We found no recurring complaint we could source to this model, and we are not going to invent one.
When/who: pick this one if the budget is tightest and a pull cord does not bother you — the watts are the same; the conveniences are what you give up.
Prices last checked November 1, 2026. The WEN price was verified that day at WEN’s own store. Westinghouse no longer lists the iGen4500 in its own store — its successor, the iGen5000, lists at $1,099 — so the $849 above is the last Amazon check, from October 27, 2026; the iGen4500 is still widely sold by retailers. We could not verify a current price for the Champion, so none is printed.
Shopping the sales? Before you pay any store, run the deal through our 60-second power-station deal check — the exact-domain rule, today’s real prices, and the card-declined checkout trap.
Three more worth a look
Honda EU3200i — smaller and lighter than everything above at about 65 pounds, with Honda’s dealer network behind it; a fit if your essentials list is short. Generac iQ3500 — 3,000 running watts with electric start, from 1,202 owner ratings averaging 4.4 stars; at the small end of the band, so check your peak first. Cummins Onan P4500i — near-twin numbers to the Westinghouse (3,700 running watts, remote start) under the Cummins name; worth a look when its price dips.
The questions that come next
What if the house is 650 sq ft with a mini-split?
The house gets smaller but the generator may not. A mini-split is efficient — often 600–1,200 running watts — but it is still a compressor with a starting surge, and in heating mode it runs nearly nonstop. Swap it in for the furnace blower in the table and the total lands in the same band. The essentials did not shrink with the floor plan.
What changes with two refrigerators?
Running watts barely move — a second fridge adds about 150. Starting watts are the risk: two compressors kicking on together can stack 800 + 800 surge watts on top of everything else. The fix is free — stagger them, one fridge first, then the second — and a 4,500 starting-watt generator still covers the house.
How long does the fuel actually last?
At the real load in the table, the Westinghouse’s 3.4 gallons is an overnight-plus supply, the Champion stretches furthest on a 20 lb propane tank, and the WEN’s 2.2 gallons means a refill roughly every 8–9 hours at half load. Budget a full tank per day of outage.
Generator or power station for a house this size?
Different tools. A power station is silent and safe indoors, but the math is hours: a fridge alone drinks about 1,200 watt-hours a day, and a station delivers only about 85% of its rated watt-hours, so a 2,000 Wh station is roughly a day and a half of fridge and nothing else. A gas generator runs the whole list for as long as you have fuel. Many houses end up with both — some pair them, running the station indoors while the generator recharges it between runs; how that pairing works is its own question, answered on its own page.
Frequently asked questions
Will a 3,500W generator run a whole 1,000 sq ft house?
It will run the essentials of one — fridge, furnace blower, sump pump, lights, internet, TV — which is what most people mean by running the house in an outage. Not central air, an electric range, or an electric water heater.
Why an inverter generator instead of a cheaper open-frame one?
Noise and clean power. Inverters in this band run 52–61 dBA against 70-plus for most open frames, and their low-THD output is safe for laptops, phones, and modern furnace controls.
Can I run it in the garage with the door open?
No. Generators belong outdoors, well away from windows and doors, exhaust pointed away from the house. Garage use, even with the door open, is a leading cause of outage carbon monoxide deaths.
Do I need a transfer switch?
Not for this plan — extension cords to the fridge, sump, and a power strip cover an outage or two a year. A transfer switch earns its cost if outages are frequent, or if the furnace and well pump need power, since neither plugs into a cord.
What size generator do I need for a 2,000 sq ft house?
For most, a 4,500 starting-watt inverter — 3,500 to 3,700 running watts. The worked 2,000 sq ft house above (well pump, chest freezer, basement sump) runs about 2,400 watts typically, with a worst-minute peak near 3,900. It is the top of the band: the same house with electric heat or central air is a different class entirely.
What size generator do I need for a 2,500 sq ft house?
Bigger than the band on this page. The worked 2,500 sq ft house peaks near 5,100 watts — past every 4,500W inverter here. Look at 5,500–7,500W dual-fuel machines or two inverters in parallel, or drop the window air conditioner and stagger the refrigerators to pull the peak back under 4,500.
How much fuel should I store for a generator?
Work it from your load, not a rule of thumb. At a 2,400W typical load the Westinghouse burns about 0.32 gallons an hour, so an 8-hour overnight run is roughly 2.5 gallons and a week of overnights is about 18 gallons; the sizer above runs the same math for each machine and house size. Store gasoline treated with stabilizer and rotate it. Propane stores indefinitely, which is the Champion’s quiet advantage.
Which one should you choose?
Choose the Westinghouse iGen4500 for the set-it-and-forget-it answer: the most running watts here, the quietest by far, remote start, and the deepest owner record. Choose the Champion if fuel flexibility matters more than quiet — propane on the shelf means the generator is ready even when the gas can is not. Choose the WEN if the budget decides: you give up electric start and some runtime, and keep every watt that matters. And if your own list looks nothing like the table — a well pump, a mini-split, a second fridge — run your numbers before you buy anything.
