Keep a router and modem online during an outage
A router needs relatively little energy. The trick is backing up the whole connection and knowing what happens when your internet provider loses power.
Count the boxes
A home connection might include a modem, router, fiber optical network terminal, and a separate network switch. Record the actual draw of each box. An adapter marked 12 V and 2 A can supply up to 24 W; that does not mean its connected device constantly uses 24 W. Use measured consumption where possible and include any upstream equipment in your home.
An eight-hour example
For a combined 20 W load, eight hours uses 160 Wh at the devices. With 85% efficiency, an 8 W inverter idle assumption, and a 20% margin, the example target is (160 ÷ 0.85 + 64) × 1.20 ≈ 303 Wh. Idle draw is meaningful at these small loads. A suitable DC solution may behave differently; use its documented conversion losses and correct voltage, polarity, connector, and current ratings.
UPS or power station?
A UPS is designed around keeping equipment powered through an interruption. A power station’s transfer behavior depends on the model. Check the documented switchover time and whether your devices tolerate it. A successful runtime calculation does not establish uninterrupted operation. Test the exact combination before relying on it.
A powered router cannot restore an upstream outage
Your provider’s local equipment may also lose power. Ask the provider what service continuity to expect and keep a separate communication plan. If the network is unavailable, conserving a phone battery may matter more than keeping Wi-Fi switched on.
Sources & further reading
Numerical examples and default device values are illustrative unless explicitly described as a measurement. Consult the manuals for your own equipment.
Make it a plan for your home.
Choose your devices and edit the assumptions.
Open the backup planner