Power Station Calculator
Stop guessing. Find out exactly which power station you need for your setup.
Start finding yoursFree. Takes about two minutes. No sign-up.
Sized the way an engineer would, answered in plain language.
Watt-hours alone undersize most setups. The Watt48 power station calculator checks capacity, continuous output, and startup surge separately, then shows why each power station fits — or doesn’t.
- Running and startup power
- Fridges, pumps, and saws need two to five times their running power for a split second when they start. We size the inverter for both.
- Real-world losses
- Inverter conversion, its idle draw, and the battery’s protected reserve eat part of the label capacity. Every number here already includes them.
- Headroom, not the bare minimum
- Loads that run for hours stay under 80% of the inverter, and the battery keeps 20% in reserve for aging and surprises.
What size power station do I need?
It depends on what you plug in and for how long. A CPAP for one night fits a compact unit at about 490 Wh. Keeping a refrigerator cold through a day-long outage takes about 1,900 Wh, and job-site saws need 1,850 W of continuous output as much as they need battery.
The table shows what the calculator recommends for common setups with typical device values. Run the power station calculator with your own devices for a size that fits yours.
| Setup | Battery capacity | Continuous output | Startup surge |
|---|---|---|---|
| CPAP for one nightCPAP, 8 h | 490 WhCompact | 50 W | No extra |
| Camping weekend12 V fridge, LED lights and phone, 2 days | 1,500 WhMid-size | 15 W | No extra |
| Remote workday with StarlinkLaptop, monitor, Starlink dish, Wi-Fi router and phone, 8 h | 1,750 WhLarge | 190 W | 250 W |
| Refrigerator through an outageRefrigerator, 24 h | 1,900 WhLarge | 190 W | 830 W |
| Job site toolsCircular saw, drill, work light and tool battery charger, 8 h | 2,600 WhLarge | 1,850 W | 2,850 W |
| Outage essentialsRefrigerator, Wi-Fi router, LED lights, phone and CPAP, 24 h | 2,850 WhLarge | 270 W | 900 W |
Typical device values in mild weather, with short-use appliances taking turns. Capacity includes inverter losses, the battery’s protected reserve, and a 20% margin for aging and surprises.
How to calculate the power station size you need
A power station has to pass three checks, not one. Battery capacity in watt-hours decides how long it lasts. Continuous output in watts decides what it can run at once. Startup surge decides whether motors and compressors can start at all.
Here is the math the calculator runs for one refrigerator through a 24-hour outage, with the same numbers it uses for your devices.
Worked example: a refrigerator for 24 hours
Battery capacity
- 150 W × 24 h, compressor running 35% of the time
- 1,260 Wh
- Inverter efficiency, 92%
- 1,370 Wh
- Inverter idle draw, 5 W for 24 h
- 1,490 Wh
- Usable share of rated capacity, 95%
- 1,568 Wh
- Reserve for aging and surprises, +20%
- 1,882 Wh
- Battery capacity to look for
- 1,900 Wh
Continuous output
- Running power
- 150 W
- Headroom for a load that runs for hours, 125%
- 188 W
- Continuous output to look for
- 190 W
Startup surge
- Power while the compressor starts
- 750 W
- Margin on the startup estimate, 110%
- 825 W
- Startup surge to look for
- 830 W
Appliance wattage chart
Typical running and startup watts for the appliances people plug into a power station most. They come from US DOE and ENERGY STAR figures, generator wattage worksheets, and manufacturer specs, and they are the values the calculator starts from.
Your appliance’s label beats any typical value: look for watts, or multiply volts by amps. Add your devices to the calculator and edit any number to match.
| Appliance | Running | Startup | Per day |
|---|---|---|---|
| Computers & connectivity | |||
| Laptop | 60 W | Same as running | 4 h |
| Desktop PC | 250 W | Same as running | 4 h |
| Monitor | 60 W | Same as running | 4 h |
| Phone | 20 W | Same as running | 1.5 h |
| Tablet | 20 W | Same as running | 2 h |
| Wi-Fi router | 12 W | Same as running | 24 h |
| Starlink | 75 W | 150 W | 8 h |
| Starlink Mini | 40 W | Same as running | 8 h |
| Camera charger | 10 W | Same as running | 3 h |
| Drone charger | 65 W | Same as running | 1.5 h |
| Entertainment | |||
| TV | 120 W | Same as running | 3 h |
| Projector | 80 W | Same as running | 3 h |
| Speaker | 40 W | Same as running | 4 h |
| Game console | 180 W | Same as running | 3 h |
| Kitchen | |||
| RefrigeratorRuns ~35% of the time | 150 W | 750 W | 24 h |
| Chest freezerRuns ~35% of the time | 100 W | 500 W | 24 h |
| 12 V fridgeRuns ~40% of the time | 45 W | 70 W | 24 h |
| Microwave | 1,100 W | 1,600 W | 15 min |
| Electric kettle | 1,500 W | Same as running | 15 min |
| Coffee maker | 900 W | Same as running | 15 min |
| Espresso machine | 1,350 W | Same as running | 15 min |
| Countertop oven | 1,500 W | Same as running | 30 min |
| Air fryer | 1,500 W | Same as running | 20 min |
| Induction cooktop | 1,800 W | Same as running | 30 min |
| Electric grill | 1,500 W | Same as running | 30 min |
| Home & comfort | |||
| LED lights | 10 W | Same as running | 5 h |
| Fan | 50 W | 75 W | 8 h |
| CPAP | 40 W | Same as running | 8 h |
| Space heaterRuns ~50% of the time | 1,500 W | Same as running | 2 h |
| Window ACRuns ~60% of the time | 700 W | 1,750 W | 8 h |
| Sump pump | 750 W | 1,500 W | 1 h |
| Well pump | 1,000 W | 2,100 W | 1 h |
| Vacuum cleaner | 1,000 W | 1,400 W | 15 min |
| Washing machine | 500 W | 1,000 W | 1 h |
| Hair dryer | 1,500 W | Same as running | 12 min |
| Tools & job site | |||
| Circular saw | 1,400 W | 2,300 W | 30 min |
| Miter saw | 1,800 W | 3,300 W | 30 min |
| Angle grinder | 1,000 W | 1,800 W | 30 min |
| Drill | 600 W | 900 W | 30 min |
| Air compressor | 1,200 W | 3,600 W | 30 min |
| Pressure washer | 1,500 W | 2,700 W | 30 min |
| Leaf blower | 1,000 W | 1,300 W | 30 min |
| LED work light | 50 W | Same as running | 8 h |
| Tool battery charger | 200 W | Same as running | 2 h |
| Vehicles | |||
| EV charging | 1,440 W | Same as running | 4 h |
| E-bike charger | 100 W | Same as running | 4 h |
A dash means the appliance needs no extra power to start. Per day is a typical time switched on.
Ready when you are.
Pick a use case, tap your devices, and see which power station fits.