Standby (whole-house) generators and portable generators serve overlapping but fundamentally different needs. A $7,500 installed standby unit kicks on automatically within 10 seconds of an outage and runs the whole house for days. A $1,200 portable unit requires you to roll it out, fuel it, plug it in, and manage loads manually — but covers most needs for one-fifth the cost.
The decision between them depends on outage frequency, what you need powered, and how much hands-on setup you're willing to do every time the grid drops. Here's the full comparison.
The headline numbers
| Portable generator | Whole-house standby | |
|---|---|---|
| Typical purchase price | $400–2,500 | $3,500–10,000 (unit only) |
| Typical install cost | $0–1,200 (transfer switch) | $3,000–6,000 (electrician + permit + concrete pad + gas line) |
| Total typical investment | $1,000–3,500 | $6,500–16,000+ |
| Output capacity | 1,000–13,000W | 10,000–26,000W |
| Fuel | Gasoline, propane, dual | Natural gas or propane |
| Runtime | Hours to days (per tank) | Indefinite (NG); days (propane tank) |
| Setup at outage | 5–10 minutes | 0 (automatic, 10-second transfer) |
| Maintenance | Oil/filter every 50–100 hr | Annual professional service ($200–500/yr) |
| Noise | 52–78 dBA | ~65–75 dBA (steady-state) |
| Expected lifespan | 1,000–2,000+ hr | 15–30 years (3,000+ hr) |
Standby generators: what you're actually buying
A standby (whole-house) generator is a fixed installation. The generator sits on a concrete pad outside the house, permanently connected to the home's electrical panel through an automatic transfer switch (ATS). The unit is fueled from a stationary propane tank (usually 250–500 gallon) or a buried natural gas line. When utility power fails, the ATS detects the outage, signals the generator to start, and transfers the house's load from utility to generator within 10–30 seconds. When utility power returns, the ATS transfers back and signals the generator to shut down. The whole process is automatic; you don't have to be home.
Standard sizes for residential whole-house: 10kW, 14kW, 18kW, 20kW, 22kW, 24kW, 26kW. A 14kW unit handles most three-bedroom homes including central AC; a 22kW unit handles most four-bedroom homes with electric loads.
What you get:
- Automatic operation — works while you're away or asleep
- Whole-house capacity — every circuit, including 240V loads
- Effectively unlimited runtime on natural gas
- Weekly self-test exercise (10–15 minute auto-run for engine health)
- Remote monitoring on most modern units (cellular or wifi connectivity)
- Quiet enclosed design — sound-deadening enclosure built in
- 15+ year service life with proper maintenance
What it costs:
The unit itself runs $3,500 (10kW) to $10,000+ (26kW Generac Guardian). Installation typically adds $3,000–6,000: electrician for ATS install, gas plumber for line tap and meter upgrade if needed, concrete pad pour, electrical permit, gas permit, jurisdictional inspection. Larger units sometimes need an upgraded gas meter from the utility ($500–1,500). Total installed: $6,500 for the smallest 10kW unit; $16,000+ for a fully configured 22kW system.
Annual maintenance contracts run $200–500/year for a service technician to change oil, replace filters, check the ATS, and verify the auto-test cycle. Most homeowners use the manufacturer-recommended dealer for the first few years.
Portable generators: what you're actually buying
A portable generator is a movable, gasoline- or dual-fuel-powered unit that you deploy during outages. It connects to the house through extension cords or, more commonly, a manual transfer switch or interlock kit on the panel. You start the generator manually, plug in the cord, flip the transfer switch, and the house's selected circuits come alive. When utility power returns, you reverse the process. Manual operation throughout.
Sizes range from 1,200W (camping inverters) to 13,000W (heavy-duty open-frame dual-fuel). For home backup, the sweet spot is 6,500–9,500W — enough for essentials plus comfort, manageable to roll and fuel, costs $700–1,300 for the generator itself.
What you get:
- One-fifth the cost of a standby system
- Flexible — same generator works for camping, tailgating, jobsites
- Easier replacement at end of life
- No fixed install — sells with the house or moves with you
- No gas line work, no concrete pad, no expensive electrical contractors
- Can be added to in stages (start with extension cords, add transfer switch later)
What it costs:
$700–1,300 for a quality 7,500–9,500W dual-fuel unit. Transfer switch or interlock kit + inlet box + cord adds $600–1,200 installed. Total typical: $1,300–2,500 fully set up. Annual maintenance is owner-doable at low cost (~$30/year for oil, plug, filter).
Which is right for you
Standby (whole-house) makes sense when:
- You have frequent outages (5+ per year, or any with multi-day duration)
- You travel frequently — automatic operation matters when you're not home
- You have medically-essential equipment (oxygen, dialysis, refrigerated medication)
- You have a sump pump in a basement with flooding risk
- You operate a home business that loses revenue per hour of outage
- Your house has loads that don't work well on portable backup (3,000+ sqft, large HVAC, multiple major 240V loads)
- You plan to stay in the house 10+ years (amortizes the install cost)
- You have natural gas service (eliminates fuel storage concern)
Portable makes sense when:
- Outages are occasional (1–4 per year, mostly under 24 hours)
- You're home during typical outages and don't mind 5–10 minutes of setup
- Your essential loads fit within 7,500W (fridge, freezer, furnace blower, well pump, lights, electronics)
- You want the flexibility for camping, jobsites, or RV use
- You can't justify the $7,000+ price gap to fully automated operation
- You rent, are planning to move, or are not certain about long-term residence
- You can't run gas service to the unit (rural, or no NG infrastructure)
The middle path: large portable + interlock
For many homeowners, a 9,500–12,000W dual-fuel portable plus a generator interlock kit produces 70% of the standby experience for 25% of the cost. The interlock lets you energize any circuit in the panel (within wattage limits) — including 240V loads like the well pump, water heater, or central AC if you manage them carefully. You still have to start the generator and flip breakers manually, but you don't lose the ability to power major appliances during extended outages.
This setup runs $1,500–2,800 total and covers most homes that aren't running massive HVAC or multiple 240V loads.
Common buyer mistakes
Oversizing the standby. A 26kW unit for a 2,500 sq ft house is usually overkill — and the gas service or propane tank needs to be sized to feed it, adding significant cost. Run a proper load calculation with the installer before signing for a "biggest available" unit.
Underestimating the install for standby. The unit price is often only half the total. Gas line work, concrete pad, electrical permit, and inspections often double the budget. Get a fully-scoped quote before assuming you can afford a standby for $5,000.
Skipping the transfer switch on portable. Running extension cords through cracked windows is a CO infiltration path. A manual transfer switch or interlock is $400–1,200 installed and dramatically improves both safety and usable circuits.
Buying portable for a house that really needs standby. If you have a basement sump pump, oxygen-dependent family member, or live in an outage-prone area, the portable path's "I'll set it up when an outage happens" model fails the cases that matter most. Standby exists for these scenarios.
The bottom line
For most homeowners with occasional outages, a quality dual-fuel portable plus interlock kit covers 90% of needs at 20% of standby cost. For homeowners with frequent or critical-load needs, a properly sized standby pays back in convenience and reliability over its 15–20 year service life. Run the math for your actual outage history and household needs before committing — the right answer is rarely the most expensive one, and rarely the cheapest.
For more on sizing the portable side, see how to size a generator for your home; for picks, see best home backup generators.
Frequently Asked Questions
How much does a whole-house generator cost installed?
Total installed cost typically runs $6,500 for the smallest 10kW unit up to $16,000+ for a 22–26kW unit with full install. Roughly half the budget is the generator unit; the other half is electrician work for the automatic transfer switch, gas plumber for fuel line, concrete pad, permits, and inspection. Get a fully-scoped quote rather than assuming the unit price is the total cost.
Can I install a whole-house generator myself?
No. Standby installation requires licensed electrical work for the ATS, licensed gas plumbing for the fuel connection, jurisdictional permits, and a final inspection. DIY installation voids the manufacturer's warranty in all cases we're aware of, and is illegal in every US jurisdiction we've checked. The install must be done by certified professionals.
How long does a whole-house generator last?
With proper annual maintenance, residential standby generators typically last 15–30 years (about 3,000+ operating hours over that span). Generac, Briggs & Stratton, Kohler, and Cummins all build to similar longevity standards. Service life depends heavily on maintenance discipline — skipping annual service shortens life dramatically.
Is a portable generator enough for hurricane-prone areas?
For 1–3 day outages, a quality dual-fuel portable with interlock kit covers essentials reliably. For Category 3+ events with 5–10+ day outages, the manual setup and fuel logistics become impractical — standby is usually the better answer for households that have experienced these events. The break point is roughly 'outages I can manage with manual setup' vs 'outages where I need to be away from the house dealing with damage.'
Do whole-house generators run during weekly tests?
Yes. Modern standby units include a weekly auto-exercise cycle (typically 10–15 minutes) to keep the engine lubricated and detect problems before they cause an outage failure. The schedule is configurable; most owners set it for a daytime slot when noise is least bothersome. The exercise cycle uses minimal fuel — about a gallon per year of natural gas.