PowerRuntime — Know What Runs. Know How Long.
Calculate Runtime
Work-through-the-outage planning

Home Office UPS Runtime Calculator

Build your exact workstation load and estimate how long your UPS, inverter or power station can keep the laptop, desktop, monitors and internet running.

Device-by-device loadWh or volts × AhPeak-power checks

Build your backup load

Enter the quantity and real wattage for each device. Use a plug-in power meter when possible; manufacturer power-supply ratings often show maximum capacity, not typical use.

Devices and backup system

Results update as you change any value.

DeviceQtyEachTotal
Laptop
W
65 W
Desktop PC
W
0 W
Monitor
W
30 W
Wi-Fi router
W
12 W
Fiber ONT / modem
W
8 W
Other equipment
W
0 W
Calculated device load before margin115 W

Backup specifications

Wh
V
Ah
Series raises voltage; it does not add Ah.
%
W
%
%
W
W
W

How this UPS runtime estimate works

A useful result needs the real device load, usable battery energy and conversion losses—not the VA number alone.

01 / BUILD THE LOAD

Add each device

The calculator totals quantity × watts for every item, then applies your safety margin for changing workloads.

02 / FIND REAL ENERGY

Reduce nameplate capacity

Usable-capacity percentage accounts for depth-of-discharge limits; efficiency increases the battery-side power required by the devices.

03 / CHECK OUTPUT

Validate power limits

Continuous device load and expected startup peak are checked separately against the UPS output limits.

Runtime = Battery Wh × Usable % ÷ ((Device load × Safety margin ÷ Efficiency %) + UPS idle watts)

VA is not battery capacity

A 1500 VA label describes apparent-power handling, not stored energy. Runtime requires watt-hours—or battery voltage multiplied by amp-hours—plus the actual load in watts. Do not enter VA as Wh.

Home office backup questions

How long will a 1500 VA UPS run a computer?

VA alone cannot determine runtime. Two 1500 VA units may contain different batteries. Enter the battery watt-hours or battery-bank volts and amp-hours, then add the real computer load.

Should I use charger wattage for a laptop?

The charger label is usually a maximum. A plug-in meter gives a better normal-use reading, especially when the laptop battery is already charged.

Why include the router and fiber ONT separately?

Many fiber connections require both devices. Backing up only the Wi-Fi router may leave the internet offline if the ONT loses power.

Does power factor affect runtime?

It can affect UPS loading and conversion efficiency. This estimator uses watts for energy calculations and a separate output-rating check; use manufacturer data for critical deployments.

OPTIONAL SHOPPING SHORTCUTS

Compare home-office backup options

Match the calculator’s total load and runtime target. Check output waveform, continuous watts, battery capacity and transfer behavior for your equipment.

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