How Many Watts Do I Need for a UPS?

How Many Watts Do I Need for a UPS?

Many friends ask when buying a UPS: "How many watts (W) do I actually need?"

First, when looking at UPS specifications, you'll see two units: VA (volt-ampere) and W (watts).

- VA is the "apparent power," which represents the UPS's "total power supply capacity."

- W is the "real power," which is the "actual power consumption" of your equipment.

The relationship between the two is: W = VA × Power Factor.

For ordinary UPS units, the power factor typically ranges from 0.6 to 0.8.

For example: a 1000VA UPS with a power factor of 0.6 has an actual output wattage of only 1000VA × 0.6 = 600W.

Second: Calculate How Many Watts You Need

Follow these steps:

1. List all the devices you want to connect to the UPS

(e.g., desktop computer, NAS, router, etc.)

2. Check the "power consumption" (W) of each device

This is usually found on the device's power label or in the user manual.

3. Add up the wattage of all devices

For example:

- Office desktop computer: 150W

- Monitor: 40W

- NAS: 50W

- Router: 15W

Total required wattage = 150 + 40 + 50 + 15 = 255W

4. Add a buffer (safety margin)

To avoid running the UPS at full capacity continuously, it's recommended to add a 20-30% buffer.

255W × 1.3 ≈ 331W

Purchasing Tips: What to Consider for Hong Kong?

For home use: If you're only protecting a desktop computer and network devices, a UPS with around 600-800W is generally sufficient.

For SOHO/small to medium businesses: If you have servers or multiple NAS units, it's recommended to choose a UPS with 1000W or more and opt for an "line-interactive" model for more stable power supply.