How the numbers work
Watts Enough? — as in, what's enough? — exists to answer one question honestly: how much backup power do you actually need. This page is the fine print, written to be read.
The method
Every runtime on this site and on our YouTube channel comes from the same three-step calculation:
- Usable capacity: we count 95% of a battery's rated watt-hours — battery management systems reserve the rest.
- Inverter loss: we count 87% efficiency converting DC to AC. Typical published range is 85–90%; we sit at the cautious end.
- Duty cycle: compressor appliances (fridges, freezers, pumps) don't draw their label wattage continuously. We use typical published cycling fractions — a standard fridge runs about 35% of the time.
Surge verdicts use a 1.5× headroom rule: a station's continuous output times 1.5 must clear your largest startup spike while everything else keeps drawing. Many stations advertise 2×; we deliberately use the conservative figure. When a manufacturer doesn't publish a surge rating we never guess — we fall back to the continuous rating, which is the safe direction.
Device figures are typical published values, not measurements of your specific appliance. Your fridge, your climate and your habits will move the numbers. That's exactly why the calculator asks about your devices instead of giving one answer to everyone — and why we round down, always. An estimate that flatters the product is worse than no estimate.
What this site will never do
- Quote prices or star ratings — they change weekly and sales lie.
- Recommend a specific product we haven't verified spec-by-spec against the live listing. (That's also why the calculator currently recommends stationclasses, not models — the verified catalogue is being built.)
- Give medical advice. If you're backing up medical equipment such as a CPAP, the numbers here are engineering estimates only — talk to your equipment provider about your actual requirements.
How we make money
Today: we don't. The calculator is free, there are no ads and no paid placements. In the future, product recommendations may carry affiliate links — meaning if you buy through them, the retailer or manufacturer pays us a commission at no extra cost to you. When that happens, every such link will be labeled, and this page will say exactly which programs we belong to. No manufacturer sees our verdicts before you do, and no commission changes a verdict: the math is public, on this page, and the same for every product.
About the narration on our channel
The voice on our YouTube channel is AI-generated. Everything it reads — the research, the scripts, the calculations, and the calculator you see running on screen — is original work by this site. We label AI use per YouTube's disclosure policy because transparency is cheap and trust is not.
Contact
Spotted an error in the math? That's the most valuable email you can send:hello@wattsenough.com. Corrections get fixed and credited.