Know what to buy before the lights go out
Add the things you need to keep running and get the battery size, generator size or solar setup that fits. Every result shows the math behind it.
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Power Station Size Calculator
Pick your appliances and get the battery capacity (Wh) and output (W) you actually need.
Power Station Runtime Calculator
How many hours will a battery run your fridge, CPAP or TV?
Generator Size Calculator
Add up running and starting watts to choose the right generator.
Solar Panel & Charge Time Calculator
How long solar panels take to recharge a battery, and how many you need.
Appliance Electricity Cost Calculator
What an appliance costs to run per day, month and year.
Appliance Wattage Chart
Running and starting watts for 38 common household appliances in one table.
New here? It takes three steps
- 1
List what has to stay on
The fridge, the internet, a CPAP, a sump pump. Only the things you'd really miss in an outage.
- 2
Run the calculator
Pick those appliances and it tells you the battery size and power you need, with the math shown.
- 3
Compare models that fit
Check the comparison chart for units that meet your numbers, and read the guide for your situation.
From camping to whole-home backup
See all 8 modelsBuying guides
More buying guidesBest Portable Power Stations for Home Backup: How to Choose by Size
How to choose a portable power station for home backup, from 1 kWh units for the fridge and internet to 3.6 kWh+ systems that can power circuits through a transfer switch.
Best Power Station for CPAP: How to Choose (and How Many Nights You'll Get)
How to pick a power station for your CPAP machine: how many watt-hours you need, why DC power doubles runtime, and which battery sizes cover 1, 2 or 3 nights.
What Size Generator Do I Need to Run a House?
Most homes need a 5,000–7,500 W generator for essentials and 10,000 W+ for well pumps or central AC. Learn how to calculate your exact size in 4 steps.
How we work
Every calculator shows its formula and every guide explains the numbers, so you can check our work. Brands don't pay for rankings. When we link to a product we may earn a commission, which is what keeps the calculators free. More about Lights On Lab.
Latest guides
All guidesBest Portable Power Stations for Home Backup: How to Choose by Size
How to choose a portable power station for home backup, from 1 kWh units for the fridge and internet to 3.6 kWh+ systems that can power circuits through a transfer switch.
Can a Power Station Run a Space Heater? (Why It's Usually a Bad Idea)
A 1,500 W space heater drains a 1,000 Wh power station in about 35 minutes. The math, and better ways to stay warm when the power is out.
Best Power Station for CPAP: How to Choose (and How Many Nights You'll Get)
How to pick a power station for your CPAP machine: how many watt-hours you need, why DC power doubles runtime, and which battery sizes cover 1, 2 or 3 nights.
Can a Power Station Run a Window Air Conditioner? (And for How Long?)
Yes, a 1,800 W+ power station can run a small window AC, but only for 1–4 hours on a 1–2 kWh battery. The math, and how to stretch runtime in a summer outage.
Can a Power Station Run a Sump Pump During a Storm?
Yes. A 1/3 or 1/2 HP sump pump needs about 800–1,050 W running and up to 2,200 W to start. See how long a power station keeps your basement dry.
Generator Safety: How to Avoid Carbon Monoxide Poisoning
Portable generators cause dozens of carbon monoxide deaths every year. Learn the safe distance, where to place a generator, CO alarm tips and warning signs.