Portable Power Station Size Calculator
Estimate the watt-hour capacity you need for a router, modem, fiber ONT, Wi-Fi access point, switch, laptop, or small home-office load during an outage.
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Quick Sizing Rule
Required capacity is load watts multiplied by runtime hours, then adjusted for inverter losses and reserve. A 35W internet setup for 12 hours usually needs around 550Wh to 650Wh.
Use measured wall watts when possible. Power adapter labels often show maximum output, not normal draw.
Your Backup Load
Common Starting Sizes
| Use case | Typical load | Practical starting size | Why |
|---|---|---|---|
| Modem + router | 18W to 30W | 256Wh to 512Wh | Enough for many short and medium outages. |
| Fiber ONT + router + switch | 25W to 45W | 512Wh to 768Wh | ONTs and switches add steady load. |
| Mesh Wi-Fi network | 35W to 70W | 768Wh to 1024Wh | Multiple nodes shorten runtime quickly. |
| Home office internet + laptop | 60W to 120W | 1024Wh or larger | The laptop or monitor often dominates the load. |
What To Read Next
For router-only runtime math, use the router backup runtime calculator. For sizing examples, read how long a portable power station can run a router. If you are deciding between automatic failover and longer runtime, compare UPS vs portable power station.
FAQ
What size power station do I need for a router?
For a basic modem and router, 256Wh can be enough for many outages, while 512Wh is a safer starting point for longer runtime.
Should I use a UPS or portable power station?
Use a UPS when seamless automatic switchover matters. Use a portable power station when longer runtime matters and a brief interruption is acceptable.
Why does the calculator add efficiency and reserve?
Portable power stations lose some energy through inverter conversion, standby draw, and real-world conditions. Reserve keeps the estimate from being too optimistic.
Buying Guide
If you want the buyer-focused version after sizing your load, read Best Power Station for Internet Outage.
Solar Generator Guide
If solar recharge is part of the plan, read Best Solar Generator for Home Office Power Outages.
Brand Comparison
Comparing compact stations? Read EcoFlow vs Jackery vs Anker for Home Network Backup.
Solar Recharge Time
If panels are part of the plan, read Solar Recharge Time for Portable Power Stations.