Generator sizing guide

Picking a home generator should be simple. But one question stops most people cold: what size do I need?

Too small, and it won't keep your heat, water, and fridge running when a storm hits. Too big, and you pay for power you'll never use. Get it right, and your home stays warm, safe, and lit — automatically — every time the grid goes down.

This free guide does the math for you. Answer a few quick questions below, and we'll email you a custom generator sizing report for your home. No guessing. No pressure.

If you are looking for more information on how our generator sizing tool works, you can find detailed information below the form.

Generator consultation

Your results will be sent to your email address within approximately 30 seconds. If you do not see the email in your inbox, please check your junk or spam folder.

Generator requirements

Home size *

How do you currently heat your home? *

What are your backup power needs? *

Charge EV during an outage? *

Refer you to installers near you? *

Do you live in a flood-prone area? *

When would you like to install? *

Contact information

First name *

Last name *

Email *

Phone number *

Address *

Province *

Postal code *

Why the right generator size matters

Your generator has one job: keep your family safe and comfortable when the power is out. The right size powers everything that matters — your furnace, well pump, sump pump, fridge, and lights — without missing a beat.

In a Canadian winter, that's not a luxury. A few hours without heat can freeze your pipes. A dead sump pump can flood your basement. The right-sized generator protects your home and your investment while your neighbours sit in the dark.

Too small vs. too big

Too small: the generator overloads and shuts off — leaving you cold at the worst moment.

Too big: you pay more up front and burn more fuel than you need.

Just right: a perfect fit for your home. That's what this guide finds.

How to get your free sizing report

It takes about two minutes.

Tell us about your home — size, heating, and what you want to keep running.

We match it to the right generator size, measured in kilowatts (kW).

You get your custom report by email — including the Generac models that fit your home.

Fill out the form below to start.

What your sizing report looks at

Every home is different, so we look at what matters:

The size of your home

How you heat it — gas, electric, or oil

Big power users like your well pump, sump pump, and air conditioner

Whether you want to run your whole home or just the essentials

Your fuel — natural gas or propane

We use these to find the smallest generator that still powers everything you need.

Generator sizing questions, answered

What size generator do I need for my house?

Most homes need a standby generator between 10 and 26 kilowatts. The exact size depends on your heating, your water system, and the appliances you want to run. The form above gives you an answer built for your home.

Which Generac generator do I need?

Generac makes home standby generators in several sizes. The right one depends on your home and what you want to power. Our free report matches you to the right Generac model — no showroom visit required.

Can a Generac run on natural gas or propane?

Yes. Home standby generators run on natural gas or propane — whichever your home already uses. You never have to fill a gas tank or haul fuel in the middle of a storm.

How long can a standby generator run?

On natural gas, it can run for days or even weeks. It starts on its own within seconds of an outage and shuts off when the power comes back — even when you're not home.

Will it power my whole house?

It can. A larger unit runs your entire home — heat, water, kitchen, and air conditioning. A smaller unit covers the essentials. Your free sizing report shows you both, so you can choose.