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Generator Sizing Tool

What size generator do you actually need?

Skip the guesswork and the upsell. Tell us about your home, and we’ll show you the right kW range — sized for real Twin Cities winters, not a sales quota.

2 min
To get a number
Free
In-home load calc
8-36 kW
Generac & Kohler

Size your generator

Move the sliders, tap the toggles. Your live recommendation updates as you go — no email, no phone number, no spam.

2,200 sq ft
Gas / Propane
Heat pump
Electric resistance
None
One central unit
Two units
Large / multi-zone
Well pump
Sump pump
Electric range
Electric water heater
EV charger
Hot tub
Home office
Medical equipment
Recommended size
22kW
Whole-home backup

Covers your full panel including AC, well, and essentials with a buffer for cold-weather starts.

Essentials3.0 kW
Heating system1.0 kW
Cooling5.0 kW
Other selected2.0 kW
+25% safety margin14 kW
Get a free in-home load calc →

What size means in practice

Generators come in standard sizes. Here’s a real-world look at what each tier handles.

8-12kW
Essentials only

Furnace blower, fridge, lights, internet. Skips central AC.

  • Small homes < 1,500 sq ft
  • Cabin & rural backup
  • Won’t run AC
14-18kW
Selective whole-home

Covers most of the panel with managed AC startup. Smart load shedding.

  • 1,500–2,500 sq ft
  • One central AC
  • Gas furnace + standard loads
22-26kW
Full whole-home

The Twin Cities sweet spot. Runs AC, well, sump, range — everything at once.

  • 2,500–4,000 sq ft
  • Two AC units possible
  • Most popular pick
30-36kW
Heavy-load homes

For all-electric homes, big estates, or homes with EV + hot tub + heat pump.

  • 4,000+ sq ft
  • Heat pump or electric heat
  • Multiple high-draw loads

Twin Cities homes we’ve sized

Three real examples from the past year. Names changed; loads are accurate.

Cottage Grove · 1,650 sq ft

1980s rambler, gas heat, single AC

  • Gas furnace + 2.5-ton AC
  • Sump pump (basement)
  • Standard kitchen, no EV
Installed
14kW Generac
Woodbury · 2,800 sq ft

2010 build, two-zone AC, well water

  • Two central AC units
  • Well + sump pump
  • Electric range, gas water heater
Installed
22kW Generac
Stillwater · 4,200 sq ft

Custom build, heat pump, EV charger

  • Heat pump w/ electric backup
  • Two AC + hot tub
  • Tesla Wall Connector + sauna
Installed
30kW Kohler

What sizing actually depends on

Square footage is a starting point, not the answer. Here’s what we look at.

Starting wattage, not running

AC compressors, well pumps, and big motors pull 2–3× their running wattage at startup. Undersized generators trip on the spike — even if they could “run” the load.

Cold weather margin

Twin Cities winters demand 15-25% more from a generator than the spec sheet says. We size for the night the storm rolls through and the temp drops to -10°F.

Load management changes the math

Modern Generac & Kohler units shed non-critical loads automatically, so you can run a 22 kW where you’d otherwise need 26 kW. We spec smart whenever it saves you money.

Fuel type matters

Natural gas runs 10–12% lower kW than propane on the same generator. If you’re on LP, we factor that in. If you’re switching, we’ll quote both.

Generator sizing FAQ

Can I just go by square footage?
No. A 2,000 sq ft all-electric home with a heat pump and EV charger needs more than double the generator of a 2,000 sq ft gas-heated home with no big loads. Square footage is a sanity check, not a calculation.
What happens if my generator is too small?
Two things, neither good. Either it trips during a high-load moment (AC startup on a 95°F day, well pump kicking on with the dishwasher running) and you lose power mid-outage. Or it runs near 100% capacity continuously, burns through fuel fast, and dies young — generators are designed to run at 50-75% load.
Is bigger always better?
No. An oversized generator costs more upfront, more to install (bigger gas line, bigger transfer switch), and runs less efficiently — generators don’t like running at 20% load any more than they like 100%. We size to your actual loads plus a 25% safety margin, not “biggest available.”
How much does a 22 kW Generac cost installed in the Twin Cities?
Typical 22 kW whole-home installs run $11,000–$16,000 depending on gas line work, transfer switch placement, electrical service distance, and concrete pad. We give a flat written quote during the in-home assessment — valid 30 days, no surprises.
Do you recommend Generac or Kohler?
Both are solid. Generac dominates the residential market — easier parts and service. Kohler runs quieter and tends to last longer in heavy-cycle use. We’re authorized for both and will quote the one that fits your home, not the one with the better margin.
Will the generator run my whole house, or just the essentials?
Depends on what you want. We can wire it whole-home (every circuit transfers), essentials-only (sub-panel with the circuits you pick), or “managed whole-home” (everything works, but smart load management staggers AC and other big loads). Most Twin Cities homeowners choose managed whole-home.
How long does the generator run during an outage?
As long as the fuel lasts. On natural gas, that’s effectively unlimited — the gas company keeps running through outages. On propane, it depends on tank size: a 500-gallon tank at 50% load runs a 22 kW generator for roughly 4-5 days. We’ll calculate runtime for your specific setup during the visit.
How do I know your sizing is honest, not upsold?
Two things. First, our written quote breaks down the load calculation — you can see exactly which appliances we counted and at what wattage. Second, we’ll show you the next size down and explain why we’re not recommending it. If a 20 kW would actually work fine for your home, we’ll tell you and quote it.

Want a real load calc, not a guess?

Free in-home assessment, written quote during the visit, valid 30 days. We measure your actual circuits.

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