How Long Can a UPS Run a Router and Modem?

A UPS can keep a router and modem powered during an outage, but the duration depends on the exact UPS, the load and the battery's condition. Use the manufacturer's runtime curve for that model; VA does not convert into hours.

How long could a power station run your internet gear?

These are planning estimates using the same preset wattages and calculation as our calculator. They apply to rated-capacity power stations, not traditional UPS batteries. Presets are starting assumptions: measure your own equipment and adjust the calculator.

The calculator allows for usable capacity, conversion losses and a safety margin. It does not model each power station's idle draw or low-load shutoff, which can matter greatly for a router. These estimates are not measured runtimes. See the calculation and its assumptions.

Try your setup in the calculator

Setup	4 hours	8 hours	12 hours
Router only	Calculate	Calculate	Calculate
Router + modem	Calculate	Calculate	Calculate
Router + fibre ONT	Calculate	Calculate	Calculate
Router + modem + switch	Calculate	Calculate	Calculate

A published UPS example

These manufacturer-published points for the APC BE600M1 Back-UPS 600VA were retrieved on Sep 11, 2026. They show why load matters. They are not a measured result for your router. Manufacturers revise these curves, so check the current source before buying.

Published load	Published runtime, Sep 11, 2026
10W	258 minutes
40W	67 minutes
80W	30 minutes

Check the manufacturer's current runtime curve before buying. We do not calculate a precise runtime between these points or extend the curve below its published range. Compare other UPS models and their sources.

Find the runtime for a UPS you already own

Identify the exact model and its battery configuration. Measure the watt draw of everything connected to the battery-backed outlets, then find that load on the manufacturer’s runtime curve. Check that the equipment also stays within the UPS output ratings.

If the published points do not cover your small load, ask the manufacturer for low-load data or test your setup. Half-load and full-load figures cannot tell you precisely how long a router will run. Battery condition, temperature and the UPS’s own power consumption also affect the result.

The UPS comparison table links to the manufacturer sources for the models we track. How Long Will a UPS Run? explains how to read them.

Why a router’s adapter rating is not its actual draw

An adapter label describes what the adapter can supply. The router may draw less in normal use. A plug-in power meter gives a better starting point for AC backup sizing than adding every adapter’s maximum rating. If you plan to power the router directly from a mini DC UPS instead, see how long a mini UPS will run a router.

The tables above use the calculator’s presets, not measurements of your equipment. Edit the setup to match your own draw. Include mesh nodes and switches, but count a combined modem/router only once.

For a power station, the calculator provides an initial capacity estimate. It does not account for every model’s inverter idle consumption. At a small router load that overhead can materially shorten runtime, and a low-load shutoff setting may turn the outlet off before the battery is empty.

UPS or power station for a long outage?

For a UPS, compare the published runtime at your load. For a power station, compare capacity alongside idle consumption, AC-output timeout settings and transfer time. Price and capacity alone do not establish whether your equipment stays online.

Standby and line-interactive UPS models have a transfer interval; they are not universally instantaneous. Many power stations also pause when wall power drops. Check the exact model’s specification and test whether the router reboots during a transfer.

If your target is four, eight or twelve hours, What Size UPS Do I Need for a Router and Modem? works backwards from the duration to the sizing checks. For the wider comparison, see UPS vs Portable Power Station.

What people miss

Fibre needs the ONT powered too. The ONT connects your router to the fibre service. An unpowered ONT leaves a working Wi-Fi network with no internet connection.

Mesh nodes add separate loads. Include each node you want to keep using, and consider how power reaches equipment in different rooms.

Some outlets may provide surge protection only. Put the equipment that must stay online on the UPS’s battery-backed outlets. Check the outlet markings and manual.

An old battery can change the answer. Published curves describe specified battery conditions. Test older batteries and follow the manufacturer’s replacement guidance.

Your provider can still fail upstream. Powering your equipment preserves the local network but does not guarantee internet service during a wider outage. Our power outage checklist covers other preparations.

Check your setup before relying on it

Start with the matching calculator link above, or use the UPS runtime comparison for a traditional UPS. Include every required network device, leave margin for battery ageing, and test both runtime and transfer behaviour before the next outage.