The Generac Guardian 22kW is the right default for most homes: $5,999 for the unit, 19.5kW on natural gas, and the largest installed base in the country, so parts and technicians are everywhere. Expect $11,000 to $16,000 installed for a whole-house setup once the transfer switch, pad, gas line, and permits are in. If you only need essentials to stay on, the Cummins QuietConnect RS13A does it for $3,899.
We compared all 13 air-cooled home standby generators worth buying on the spec that decides it and almost nobody publishes: what each one actually makes on natural gas.
Standby generators are advertised at their propane rating. Natural gas carries roughly 10% less energy per unit volume, so the same engine makes less power burning it — and most homes burn natural gas. A “22kW” Generac is a 19.5kW generator on a gas line. A “26kW” is 22.5kW.
3 units here break the pattern and hold full output on natural gas: Briggs & Stratton PowerProtect 22kW, Generac Guardian 14kW, and Cummins QuietConnect RS13A. Every ranking and every price-per-kilowatt figure on this page uses the natural-gas number. If you're on a buried propane tank, add the derate back.
The safe default, and the argument is short: more of these are in the ground than anything else here, so every electrician has wired one and parts sit on local shelves. You pay for that with a 2.5kW natural-gas derate.
Full specs, pros and cons →
The one unit here that doesn't quietly shrink when you connect it to a gas line. Briggs' NGMax tuning delivers all 22,000 watts on natural gas, where Generac's 22kW drops to 19,500 and Kohler's 20kW to 18,000 — so on the fuel most homes actually burn, this is a size class up on both for the same money. At $274 per usable kilowatt it's the cheapest real power on this page, by a margin nothing else closes. The Vanguard commercial V-twin, the 186-mph-rated aluminum enclosure and the 7-year warranty are supporting arguments; the fuel tuning is the reason.
Full specs, pros and cons →
Air-cooled generators top out here, and Kohler's flagship makes 24kW on natural gas against Generac's 22.5kW from the same nominal 26kW — the smallest derate at the top of the class. Dual compressors, well pump, electric range, without stepping up to liquid-cooled money. The warranty is written in hours rather than optimism: five years or 2,000 of them.
Full specs, pros and cons →
41kVA of motor-starting capacity, which in practice means it spins up a 5-ton compressor without sagging the rest of the house. Rivals this size manage the same inrush by shedding other circuits; the 20RCA just starts it. Buy it if your sizing problem is one enormous load rather than square footage.
Full specs, pros and cons →
65 dB at 23 feet while still starting a 5-ton AC — most of this class runs 67 to 70. That gap is the one you hear at 2 a.m. through a bedroom window on night four of an outage, and again every Wednesday when it exercises.
Full specs, pros and cons →
A 10-year warranty, double what Generac, Kohler or Cummins offer, with a 200-amp service-entrance transfer switch already in the box for about five thousand dollars. The aXis trick is Power Line Carrier: the generator talks to the switch over your existing house wiring, so the install skips a control-wire run. The catch is worth stating plainly — 12.5kW on natural gas puts this at essentials-plus-one-AC, not true whole house.
Full specs, pros and cons →
The cheapest way onto a pad with a genuine commercial-pedigree engine, and it holds all 13kW on natural gas with no derate at all, so its real output beats several nominally larger units here. It won't run central air. That's the trade: furnace, fridge, well pump, sump pump, lights and internet, automatically, under four thousand.
Full specs, pros and cons →Size to your largest starting load, not your square footage. A 5-ton air-conditioner compressor's inrush is what strands an undersized generator; floor area only changes the number of small loads. These are natural-gas kilowatts.
| Home | Size | What it covers | Generator (NG) |
|---|---|---|---|
| Essentials only | Any size | Furnace blower, fridge/freezer, well pump, sump pump, lights, internet | 9-13kW |
| Small home | Under 2,000 sq ft | Essentials plus one 2-3 ton central AC | 14-17kW |
| Average home | 2,000-3,000 sq ft | Essentials plus one 4-5 ton AC, electric range or dryer | 18-20kW |
| Large home | 3,000-4,500 sq ft | Two AC compressors, well pump, range, dryer, hot tub | 20-24kW |
| Very large home | 4,500+ sq ft | Dual 5-ton AC, electric heat, pool equipment, shop | 24kW+ or liquid-cooled |
Working from a load list instead? Walk through the wattage math →
Budget roughly double the sticker. The generator is the only line item the manufacturer advertises, and it's a little under half the check you write. Generac prices broken down model by model →
| Line item | Typical range | Notes |
|---|---|---|
| The generator itself | $3,900 - $7,300 | The only number on the box |
| Automatic transfer switch | $500 - $1,500 | Included on some SKUs — check before comparing prices |
| Concrete or composite pad | $200 - $700 | Plus excavation if the site needs leveling |
| Gas line and meter upgrade | $1,000 - $3,500 | The wildcard: distance to the meter, and whether the utility must upsize it |
| Electrical labor | $1,500 - $3,500 | Panel work, conduit, bonding, startup and commissioning |
| Permits and inspection | $200 - $800 | Required nearly everywhere; two inspections in most jurisdictions |
| Essentials setup (10-14kW) | $8,000 - $11,000 | |
| Whole-house setup (18-26kW) | $11,000 - $16,000 | |
| Annual maintenance after that | $150 - $400/yr | |
Sorted by real natural-gas output. “Advertised” is the propane rating on the box; “On NG” is what a natural-gas home receives.
| Generator | Advertised | On NG | Price | $/kW (NG) | Noise | Warranty |
|---|---|---|---|---|---|---|
| Kohler 26kW RCA | 26kW | 24kW | $7,099 | $296 | 70 dB | 5-year/2,000-hour limited |
| Generac Guardian 26kW | 26kW | 22.5kW | $6,849 | $304 | 67 dB | 5-year limited |
| Briggs & Stratton PowerProtect 22kW | 22kW | 22kWno derate | $6,037 | $274 | 68 dB | 7-year limited |
| Generac Guardian 24kW | 24kW | 21kW | $7,249 | $345 | 67 dB | 5-year limited |
| Generac Guardian 22kW | 22kW | 19.5kW | $5,999 | $308 | 67 dB | 5-year limited |
| Kohler 20kW RCA | 20kW | 18kW | $5,699 | $317 | 70 dB | 5-year/2,000-hour limited |
| Cummins QuietConnect RS20A | 20kW | 18kW | $5,926 | $329 | 65 dB | 5-year/2,000-hour limited |
| Generac Guardian 18kW | 18kW | 17kW | $5,279 | $311 | 65 dB | 5-year limited |
| Generac Guardian 14kW | 14kW | 14kWno derate | $4,889 | $349 | 65 dB | 5-year limited |
| Cummins QuietConnect RS13A | 13kW | 13kWno derate | $3,899 | $300 | 65 dB | 5-year/2,000-hour limited |
| Champion aXis 14kW | 14kW | 12.5kW | $4,999 | $400 | 62 dB | 10-year limited |
| Kohler 14kW RCA | 14kW | 12kW | $5,449 | $454 | 69 dB | 5-year/2,000-hour limited |
| Generac Guardian 10kW | 10kW | 9kW | $4,619 | $513 | 61 dB | 5-year limited |
For most homes the honest answer is 18-22kW measured on natural gas, not the propane rating on the box. Essentials alone — furnace blower, fridge, well pump, sump pump, lights, internet — fit inside 9-13kW. Adding one central air conditioner pushes you to 14-18kW; two AC compressors or electric heat puts you at 22kW and up. Size to your largest starting load, not your square footage: a 5-ton AC compressor's inrush is what strands an undersized generator, and no amount of floor space changes that.
Budget roughly double the sticker. A $6,000 whole-house unit typically lands between $11,000 and $16,000 installed once you add the transfer switch, concrete pad, gas line work, electrical labor, permits, and inspection. Smaller 10-14kW essential-circuit setups come in around $8,000 to $10,000. The gas line is the wildcard — if the utility has to upsize your meter to feed the generator, that alone can add several thousand. Get at least three quotes, and get them before storm season, because post-storm pricing spikes are real.
Natural gas carries roughly 10% less energy per unit volume than propane, so the same engine makes less power burning it. Manufacturers advertise the higher propane number. In practice a Generac 22kW makes 19.5kW on natural gas, a Kohler 20kW makes 18kW, and a Generac 26kW makes 22.5kW. Two units break the pattern: the Briggs & Stratton PowerProtect 22kW is tuned to hold all 22kW on natural gas, and the Cummins RS13A holds all 13kW. If your home runs on a gas line — most do — compare the natural-gas column and ignore the sticker.
For most homes under about 3,500 square feet with one air conditioner, yes — comfortably, with the AC running. For larger homes with two compressors it works, but with load management: the controller sheds a second AC or an electric water heater for a few seconds while a big motor starts. That's normal and you rarely notice it. What a 22kW will not do is run two 5-ton compressors, an electric range, and an electric dryer simultaneously with no load shedding at all. If that's the requirement, you're shopping 24-26kW or liquid-cooled.
All three are genuinely reliable engines, and the failure reports cluster around controllers and installers rather than the motors. Generac's advantage is ubiquity: the most units in the field, the most technicians who've serviced them, and parts availability everywhere — which matters more than spec-sheet differences when something fails during an outage. Kohler's advantage is build quality, notably the aluminum enclosures that survive coastal salt air and the higher motor-starting surge. Cummins sits between them on price and leads on noise. The installer you pick will affect your ownership experience more than the brand will.
Air-cooled standby generators are generally rated for 2,000 to 3,000 running hours, which for a home that loses power occasionally translates to 20 to 30 years — the weekly exercise cycle accumulates only about 10 hours a year. In practice, units get replaced because a controller board or transfer switch fails and parts stop being made, not because the engine wears out. Annual oil and filter changes are the single biggest factor, and skipping them is the most common way owners cut that lifespan in half.
Almost certainly yes — typically both an electrical and a gas/mechanical permit, with separate inspections. This is not bureaucracy worth routing around: the inspection catches the bonding, clearance, and gas-sizing mistakes that you cannot see and that make the difference between a generator and a hazard. NFPA 37 requires 18 inches of clearance from the enclosure and 5 feet from openable windows and doors on most units. An unpermitted install is also the first thing a homeowner's insurer looks for after a fire.