About & Affiliate Disclosure

Who writes this site?

David Westbrooks · Editor

I build the sizing calculators and write the guides on this site. The work behind the numbers is research and arithmetic, not generator testing: appliance wattages come from published generator manufacturer sizing guides and appliance wattage references, the formula is written out below, and every wattage in the calculator can be replaced with your own nameplate reading.

No manufacturer pays to appear here and nothing on this site is a sponsored placement. Where a guide cites a figure, it says where the figure came from, and where the reference tables are typical rather than exact, the page says that too.

Why does this site exist?

Most pages that answer "what size generator do I need" are long articles with a chart and no tool. You read through them, guess at your own numbers, and still come away unsure. This site is the tool instead.

The point is transparency. Every number the calculator uses is visible, the formula is written out below, and you can change any wattage you disagree with. If you trust your appliance's nameplate more than our table, use your number. The math does not care.

How does the sizing math work?

There are two numbers that matter on a generator: how much it can run continuously, and how much it can briefly handle at startup. Motors draw far more for the first second or two than they do while running, and that startup spike is what causes most undersized-generator failures.

So the calculator works in three steps:

The important detail is step 2. The calculator adds the surge delta, meaning the surge watts minus that appliance's running watts, and only for the largest single motor. It does not add every appliance's surge together. Adding all the surges at once would inflate your number badly, because appliances do not all start in the same instant.

Step 3 applies a 20% buffer so you are not running the generator at its absolute ceiling, and the result is rounded up to the next 100 watts. The model shown next to your result is then the smallest generator whose continuous rating covers that number, because the running rating, not the peak rating on the box, is what limits what you can power at once.

Where do the appliance wattage numbers come from?

The appliance table covers 47 common household loads, grouped into HVAC and cooling, essentials, kitchen, electronics, laundry and water, and tools. The values are typical running and starting watts for each appliance class, drawn from published generator manufacturer sizing guides and appliance wattage references.

They are deliberately typical rather than exact, because two refrigerators of the same size can differ by a hundred watts. That is why every wattage in the calculator can be edited, and why the tool tells you to check your own nameplate before you buy anything. If your equipment disagrees with our table, your equipment wins.

How does this site make money?

This site participates in the Amazon Services LLC Associates Program. When you click a product link and buy something, the site may earn a commission. You pay the same price you would have paid anyway.

Here is the part that matters to you as a reader: the recommendation is generated from your calculated load, not the other way around. The calculator works out what size you need first, then matches that number to a generator class. There are also free-to-use pages here with no product links at all, and the wattage chart and comparison guide are two of them. Nothing on this site is a sponsored placement, and no manufacturer pays to appear.

If a number on this site is wrong, that costs us more than it costs you, so the incentive is to get the math right rather than to push the biggest generator.

What is this site not?

This is a planning tool, not an electrical design service. It does not know your home's wiring, your panel capacity, or your local code requirements, and it cannot tell you whether a transfer switch or an interlock kit is appropriate for your setup.

Before you buy or connect a generator, verify rated running and starting watts against the nameplate, and have a licensed electrician check the installation. Never run a generator indoors, in a garage, or in any enclosed or partially enclosed space, because of carbon monoxide.

What about privacy?

There are no accounts and no email signup. One first-party analytics cookie tells us which calculators and guides actually get used; it is not advertising, and your appliance selections stay in your own browser so they never leave your device. The full detail is on the privacy page.