About Watt48
An independent calculator that tells you which portable power station fits the devices you want to run.
For a workday away from the outlet, a weekend off-grid, a job site, or the next outage at home: tell Watt48 what you plug in and for how long. It works out the battery and output you need, then shows which real models fit and why.
Free. About two minutes. No sign-up.
What Watt48 does
Watt-hours alone undersize most setups. Watt48 works out three separate numbers from your devices and how long they run, then checks real power stations against all three, plus the outlets each device needs.
- Battery capacity
- How much energy your devices use over the whole plan, including inverter losses, the inverter’s own idle draw, and the battery’s protected reserve.
- Continuous output
- The power a station has to supply for hours on end, sized with headroom so it never runs at its limit.
- Startup surge
- The split-second spike when a fridge, pump, or saw starts, often two to five times its running power.
Who it’s for
Work, everyday life, the outdoors, or something else entirely. The use case you pick decides which devices come first, a sensible runtime, and how much weight is reasonable to carry.
Electronics
Laptops, monitors, routers, and Starlink for a remote workday or a mobile office.
Outdoor
A car fridge, lights, phones, and cameras for camping, overlanding, and vanlife.
Work
Saws, drills, compressors, and battery chargers on job sites and remote shifts.
Home
The fridge, router, lights, and a CPAP through a power outage.
Other
EV top-ups, RVs, e-bikes, or any mix from the full device catalog.
How it works
Four short steps. Your answers are saved in your browser as you go.
Use case
Choose what you’re powering for. It sets which devices come first and a starting runtime.
Devices
Tap what you’ll plug in from 46 common devices, or add your own. Every wattage can be edited, because your device’s label beats any default.
Usage
Say how long you need power, whether things run at the same time, and how cold it will get.
Recommendation
See the capacity, output, and surge you need, and the power stations ranked by how well they fit, with the reasons behind each.
What you can count on
Watt48 is built to give you an answer you can check for yourself, not a sales pitch.
- Independent
- Watt48 doesn’t sell power stations. Units are ranked by how well they fit your plan; price and brand never change the order.
- Every number explained
- Each figure comes from your input, a product’s published specs, or a documented assumption, and the results page shows the math behind it.
- Headroom built in
- Loads that run for hours stay under 80% of the inverter, and the battery keeps 20% in reserve for aging and surprises.
- Straight answers
- When nothing in the list can run your setup, Watt48 says so and tells you what would change that, instead of recommending a unit that won’t cope.
- Private by design
- No account, no sign-up, and no cookies. Your setup stays in your browser. Read the Privacy Policy.
Where the numbers come from
- Power station specs, photos, and prices come from the public GalaxyAX/power-station dataset. The site refreshes its copy every hour and checks each record before using it.
- Device wattages are typical values from generator wattage worksheets (Honda, Champion), US DOE and ENERGY STAR data, and manufacturer specs.
- The sizing accounts for inverter efficiency and idle draw, the battery’s protected reserve, capacity lost in the cold, and the startup surge of motors and compressors.
- Missing specs are treated cautiously: a station without a published surge rating gets no surge credit beyond its continuous output.
Worth knowing
- Results are estimates for planning. Check the manufacturer’s specifications before you buy; the Terms of Use explain more.
- Recommendations cover base units. Add-on batteries are listed as a spec, not suggested as a setup.
- Sizing assumes no recharging during your plan. Solar input is listed, not modeled.
- Figures use US units and prices: pounds, degrees Fahrenheit, and US dollars.
Ready to size your setup?
Pick a use case, tap your devices, and see which power station fits.