The Generator Wattage Calculator That Saves You Time and Money
Free, and it takes about a minute to answer a few questions about your devices. We calculate the exact watts you need, so you buy the right size the first time — not an underpowered unit that fails you or an oversized one you overpaid for.
Free forever · No signup required · No spam, ever
Built after my own underpowered-generator mistake
One of 139+ real products we compare against your actual load
“I built this free tool after making an expensive generator-buying mistake myself. I chose a unit that looked powerful enough on the product page, but once I connected the devices I actually needed, it could not handle the load. This calculator exists to help you avoid the same problem.”
Rey, GeneratorFit Founder
I'm choosing a generator for...
How it works
Tell us what you'll power
Pick your use case and the devices you need to run — or search for them by name.
We calculate the real numbers
Running watts, startup surge, daily energy use, and recommended battery capacity — done for you.
Get your personalized plan
We email you a clear, practical recommendation — no guesswork, no oversized purchase.
A few of the real products we compare
Every match comes from our own catalog of 139+ generators and portable power stations — real specs, not manufacturer marketing copy.
How many watts generator do I need?
There's no single number that works for everyone — it depends on what you're actually running. Our free generator wattage calculator adds up the real running and startup watts for your specific devices, so you know exactly how many watts in a generator you need before you buy, not after.
It works the same way whether you're sizing a home generator for backup power during outages, a portable generator for camping or a job site, or a dedicated backup generator for your whole house. Tell us what you're running, and we'll calculate the size of generator for your home — or wherever you need it — in about a minute.
Technical fit comes first, always
We evaluate whether a product can actually handle your load before we ever consider commercial priority. If nothing fits, we'll tell you that instead of pointing you to the wrong product. Read our calculation methodology.
Frequently asked questions
Is this actually free?
Yes. The calculator, your personalized results, and the follow-up email are all free — the only thing we ask for is an email address to send your results to.
Do you sell the generators yourselves?
No. We compare real specs across our catalog and link out to retailers like Amazon or the manufacturer's own site. We may earn a commission from some of those links, but technical fit is always checked first — see our methodology.
How is this different from just reading spec sheets?
It does the math you'd otherwise do by hand — adding up running watts, checking the single highest startup surge, and matching that against real product specs — instead of you cross-referencing a dozen listings yourself.
What if nothing in your catalog actually fits my needs?
We'll tell you that directly instead of pointing you to the closest thing that doesn't really work. Fit comes before any commercial consideration, every time.