The storm hits, the power drops, and nothing in your house even flickers. The generator out back already started, switched your home over, and you barely noticed. That is what a home standby generator does, and this guide walks you through choosing the right one.
A standby is a bigger commitment than a portable, so it pays to get it right the first time. Below we cover how they work, how to size one for your home, the fuel and install basics, and the units we carry that fit each size of house.
Last updated: June 2026 | Written by the Mighty Generators expert team | Authorized dealer since 2023 | (888) 775-9048
Why trust Mighty Generators?
We are an authorized dealer for Cummins and Briggs & Stratton, the two standby brands we carry. We sell them, we stock them, and we help homeowners size them every day. Got a question before you buy? Call (888) 775-9048, the line answers 24/7, with specialist callback during business hours.
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1. How a Home Standby Works
A standby generator sits permanently outside your home, like an AC condenser, and wires into your electrical panel through an automatic transfer switch. When the grid goes down, the transfer switch senses it, starts the generator, and moves your home onto generator power within seconds. When utility power returns, it switches you back and shuts the generator off. You do nothing.
It runs on natural gas or propane, not gasoline, so there is no fuel to haul, no cords to run, and nothing to start by hand. On a natural gas line, it can run for the length of the outage.
2. Is Standby Right for You?
A standby is the right call when you want the whole house covered automatically. Here is how it stacks up against the alternatives.
🏠 Choose a standby if you...
- Want the house to stay on by itself
- Need to run central AC, well pump, or a furnace
- Face outages that last hours or days
- Have natural gas or room for a propane tank
- Plan to stay in the home for years
🔋 A portable or battery may fit better if you...
- Only need to cover essentials
- Want a lower up-front cost
- Rent, or move often
- Want something you can take camping too
Not sure yet? Our sizing calculator compares both paths for your loads in about a minute.
3. How to Size It
Standby generators are rated in kilowatts (kW). The right size depends on what you want to run at once, with central AC and well pumps being the heavy hitters because of their startup surge. As a starting point:
| Home Size | Typical Size | What It Covers |
|---|---|---|
| Under 2,000 sq ft | 13kW | AC, fridge, and essential circuits for most smaller homes |
| 2,000 to 3,500 sq ft | 17 to 20kW | Central AC, major appliances, and critical circuits at once |
| 3,500+ sq ft | 22 to 26kW | Full whole-home coverage without choosing circuits |
| Very large / light-commercial | 25 to 30kW | Large homes with heavy simultaneous loads |
There are two ways to cover a home. A whole-home setup powers every circuit and usually needs a larger unit. A managed setup uses load management to prioritize your important circuits, which lets a smaller, lower-cost unit do more. Your installer can advise which fits your panel.
Get a size for your exact loads with the free Generator Sizing Calculator, or browse the Generator Size Chart.
4. Air-Cooled vs. Liquid-Cooled
Most homes run on air-cooled units, which cover the common 13kW to 26kW range and install as a single outdoor unit. Liquid-cooled units use an engine cooling system like a car, run cooler under sustained heavy load, and suit very large homes or light-commercial use. That is where the 25kW and 30kW models fit. If your home is large or you plan to run heavy loads for long stretches, ask us which side of that line you fall on.
5. Natural Gas vs. Propane
🔵 Natural Gas
Connects to your home gas line and never runs out, so it is the simplest choice for long outages. You need existing gas service at the property.
🟡 Propane
Stores for years without going bad and burns clean. Runtime depends on tank size, and your installer sizes and connects the tank. The right answer when you do not have natural gas.
Most standby units we carry run on either fuel, so this comes down to what is available at your home.
6. What Installation Involves
A standby generator is a permanent installation. It needs a licensed electrician for the transfer switch and panel work, a gas professional to connect natural gas or propane, a level pad to sit on, and local permits and inspection. This is not a DIY job, and backfeeding a generator into a wall outlet is dangerous and illegal.
We sell the unit and ship it free on orders over $250. The installation is arranged separately with a local licensed pro. If you need one, we can help.
Connect with a local installer, or book a home standby consultation and we will walk you through it.
7. Key Features to Look For
- Transfer switch type. Whole-home covers every circuit; a managed switch lets a smaller unit prioritize the circuits you care about.
- Fuel flexibility. Units that run on both natural gas and propane keep your options open.
- Cold-weather rating. If you are in a hard-winter climate, look for a cold-weather option that keeps the unit starting reliably at low temperatures.
- Remote monitoring. Wi-Fi monitoring lets you check status and self-test results from your phone.
- Noise level. Quieter enclosures keep the peace with neighbors during long runs.
- Warranty. Coverage varies by model, so check the warranty details on each product page before you buy.
8. Brands We Carry
Cummins
Cummins builds the Quiet Connect standby line on commercial-grade engines, with cold-weather rated options for harsh climates and liquid-cooled models at the top of the range. A strong pick if you want proven engine quality or live where winters are severe.
Briggs & Stratton
Briggs & Stratton covers the popular residential sizes with the PowerProtect line and reaches 30kW with the Fortress series for larger homes. A practical choice across the common 13kW to 26kW range. Check each product page for current warranty terms.
9. Top Picks by Home Size
These are the standby units we carry and recommend most, grouped by the size of home they fit. All are in stock and ship free on orders over $250. See each product page for current pricing and warranty.
| Home Size | Units We Carry |
|---|---|
| Under 2,000 sq ft (13kW) | Cummins RS13A 13kW · Briggs & Stratton 13kW PowerProtect |
| 2,000 to 3,500 sq ft (17 to 20kW) | Cummins RS17A 17kW · Briggs 18kW + 200A switch · Cummins RS20AC 20kW |
| 3,500+ sq ft (22 to 26kW) | Briggs 22kW + 200A switch · Briggs 26kW + 200A switch |
| Very large / light-commercial (25 to 30kW) | Cummins RS25 25kW · Briggs 30kW Fortress · Cummins RS30 30kW |
10. Mistakes to Avoid
- Sizing off square footage alone. Your real number comes from the loads you run at once, especially central AC and well pumps. Size to the loads, not just the house.
- Forgetting the fuel supply. Natural gas needs an adequate line; propane needs a tank sized for real runtime. Sort this out before install day.
- Treating it as a DIY project. Standby installs require a licensed electrician and gas pro, plus permits. Skipping that is unsafe and fails inspection.
- Ignoring the transfer switch decision. Whole-home versus managed changes both your coverage and your unit size. Decide it up front.
- Skipping self-test and maintenance. Standby units run a weekly self-test. Keep up with service so it starts when you need it.
11. Frequently Asked Questions
What size standby generator do I need?
A home under 2,000 sq ft is usually covered by 13kW, a 2,000 to 3,500 sq ft home by 17 to 20kW, and a larger home by 22kW or more. The exact size depends on your loads. Run our sizing calculator for a number specific to your home.
Natural gas or propane?
If you have a natural gas line, use it for unlimited runtime. If not, propane is the answer, with a tank your installer sizes. Most units run on either.
Can I install it myself?
No. A standby needs a licensed electrician and gas pro, plus permits and inspection. We ship the unit; the install is arranged with a local pro.
How long can it run?
On natural gas, as long as the outage lasts. On propane, as long as the tank holds out. Either way, far longer than a portable.
How much does it cost?
Equipment price depends on size, see each product page for current pricing. Installation is a separate cost quoted by your local installer.
Ready to size your standby?
Run the sizing calculator, browse the standby collection, or call (888) 775-9048 anytime. The line answers 24/7, with specialist callback during business hours.
Mighty Generators. Authorized dealer for Cummins and Briggs & Stratton standby generators. Free shipping and free returns on orders over $250. No restocking fees.