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Generac Generator Sizing Guide

Which Generac Generator Do I Need?

Generac Guardian sizing chart by home size — from the 7.5kW PowerPact to the 22kW Guardian. Find the right model for your square footage, appliances, and AC tonnage.

6 modelsGuardian lineup covered
7.5–25 kWSize range
#1 SellingHome standby brand in US

Quick Answer

The Generac Guardian 14kW is the right choice for most US homes (1,500–2,500 sq ft) with gas appliances and 2–3 ton central AC. For larger homes or all-electric appliances, choose the 18kW or 22kW. For small homes under 1,200 sq ft with no AC: the 10kW is sufficient.

Most Popular
14 kW Guardian
Large Homes
18–22 kW
Small Homes
10 kW
All-Electric
18 kW minimum
Published Updated Reviewed by Generator Size Calculator Editorial Team

Key Takeaways

  • 1The Generac Guardian 14kW is America's best-selling home standby — right for most 1,500–2,500 sq ft homes.
  • 2All-electric homes need 4–6 kW more than equivalent gas-appliance homes due to electric water heater and range loads.
  • 3Central AC tonnage drives standby sizing more than square footage — know your AC size before speccing.
  • 4Generac Guardians include Wi-Fi monitoring (Mobile Link app) — check on your generator from anywhere.
  • 5Annual service ($150–$400) is required to maintain the Generac 5-year warranty.

Generac Generator Sizing Chart — All Models

All Guardian and Protector models run on natural gas or LP. Installed cost includes ATS, electrical work, gas line, pad, and permits.

Generac PowerPact 7.5kW

Small home or apartment, gas appliances only, no central AC

Entry-level — no central AC support

Home Size
Under 1,000 sq ft
Unit MSRP
$1,949
Installed
$5,500–$7,500
0 kW7.5 kW rated output27 kW
Generac Guardian 10kW

Small home with gas appliances and 1.5-ton central AC

Cannot run 2+ ton AC comfortably

Home Size
Under 1,200 sq ft
Unit MSRP
$3,299
Installed
$6,500–$9,000
0 kW10 kW rated output27 kW
Generac Guardian 14kWMost Popular

Medium home, gas appliances, 2–3 ton central AC

America's #1 best-selling home standby

Home Size
1,500–2,500 sq ft
Unit MSRP
$4,499
Installed
$8,000–$11,000
0 kW14 kW rated output27 kW
Generac Guardian 18kW

Larger home, all-electric appliances, 3.5-ton AC

Best value for larger homes

Home Size
2,000–3,000 sq ft
Unit MSRP
$5,499
Installed
$10,000–$13,500
0 kW18 kW rated output27 kW
Generac Guardian 22kW

Large home, all-electric, 4-ton AC, EV charging

Powers virtually any residential load

Home Size
2,500–4,000 sq ft
Unit MSRP
$6,099
Installed
$12,000–$16,000
0 kW22 kW rated output27 kW
Generac Protector 25kW

Very large home, commercial, multiple HVAC systems

Liquid-cooled — commercial grade

Home Size
3,500+ sq ft
Unit MSRP
$8,999
Installed
$14,000–$20,000
0 kW25 kW rated output27 kW

Generac Guardian vs. Protector: Which Series Is Right for You?

Generac makes two main residential/light-commercial standby lines:

  • Guardian Series (7.5–22 kW): Air-cooled engines. For residential use up to ~4,000 sq ft. Most popular for homes. Lower upfront cost, 100-hour service intervals, 5-year warranty.
  • Protector Series (25–60 kW): Liquid-cooled engines. For very large homes, light commercial, and critical facilities. Higher cost and complexity, but designed for extended runtime and continuous use. 5-year warranty, 200-hour service intervals.

For the vast majority of homeowners, the Guardian series is the right choice. The Protector is overkill for residential use unless you have an unusually large home or commercial property.

How to Use the Generac Sizing Chart

The easiest way to confirm a Generac model for your home is to use our generator size calculator to get your total running watts and surge watts. Then match that number to the Generac Guardian model that exceeds it:

Calculator OutputGenerac Model
Under 7,000 running wattsGuardian 10kW
7,000–10,500 running wattsGuardian 14kW
10,500–14,400 running wattsGuardian 18kW
14,400–17,600 running wattsGuardian 22kW
Over 17,600 running wattsProtector 25kW+

Generac recommends selecting a model with at least 20% headroom above your calculated load — the same 80% rule used by electricians and our calculator.

Where to Buy a Generac Generator

Generac generators are available through authorized dealers (best for installation and warranty service), Home Depot, and online retailers. For whole-house standby installation, always use an authorized Generac dealer — they handle permits, connect to your gas line, install the ATS, and register the warranty.

Find Generac dealers at generac.com/where-to-buy. Get at least two dealer quotes — installation costs vary 20–40% between dealers in the same market.

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Get the exact kW requirement for your home before calling dealers — prevents both undersizing and upselling.

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Frequently Asked Questions

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