Free calculator · Infrastructure

UPS and inverter runtime calculator

How long will your backup power keep the internet, network and cameras running when the power goes? Tick what you'll keep on, enter your battery, and see the runtime. Or set a target and see the battery you need.

1. What stays on during an outage
DeviceWatts eachHow many
Starlink (Standard kit)Starlink lists an average of 75–100 W
Router or firewall
Fibre or cable modem (ONT)
Network switch
Wi-Fi access point
IP cameraMost draw 4–7 W; infrared at night uses more
Camera recorder (NVR/DVR)
Laptop
Desktop PC with monitor
POS terminal or till

Figures are typical. Check the label or adapter on each device for its actual wattage.

2. Your battery
Ah

Batteries in series raise the voltage instead; choose the bank voltage above.

Draining lead-acid below about half shortens its life.

%

85% is typical; small UPS units can be lower.

hours
Estimated runtime
2 h 38 min
At a steady load, with healthy batteries
Total load
194 W
Usable energy
510 Wh
Battery needed for 8 hours
304 Ah
At 12 V, lead-acid

Real runtime is usually shorter: batteries lose capacity with age and heat, and high loads drain them faster. Treat this as a planning estimate, and protect equipment with surge protection.

Want a backup power plan that actually lasts?

We size UPS and inverter setups for Starlink, networks and CCTV, and set up automatic failover so your business stays online.

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Preparing for storms? See our hurricane season IT checklist.

More free resources

Hurricane season IT checklistRead more →Starlink and site readiness checklistRead more →Downtime cost calculatorRead more →Starlink InstallationRead more →
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