Device Running-Cost Calculator

An always-on NAS, hub or PoE camera quietly adds up. Tell us a device's power draw, how many hours a day it runs and your electricity rate, and we'll show what it really costs — per day, month and year — so you can decide what's worth leaving on. Honest arithmetic, no sign-up.

1. The device (pick a typical one, or enter your own)

These are typical ballpark figures to get you started — your exact device may differ. For real numbers, read the watts off the label or a plug-in energy monitor and use Custom.

2. Power, hours & your tariff

Use your own unit rate from a recent bill (it's the p/kWh figure) — prices vary by supplier, tariff and region, so we don't assume one for you.

Running-cost questions, answered

How is the cost worked out?

It's the standard energy sum: kilowatt-hours = watts ÷ 1000 × hours, and cost = kWh × your unit rate. So a 30 W NAS left on all day uses 30 ÷ 1000 × 24 = 0.72 kWh a day, and at 25p/kWh that's about 18p a day, roughly £66 a year. We just do that maths for the day, month and year.

Why don't you assume a UK electricity price?

Because there isn't one. Unit rates change with your supplier, tariff type, region and the energy price cap, and they move over time. A figure we baked in today could be wrong for you and would quietly make every result inaccurate — so we ask for the rate from your own bill instead of pretending to know it.

Is the label wattage the real draw?

Usually not — the rating on the label is often the maximum, while real-world draw is lower and varies with load (a NAS spins down, a camera idles). For an accurate figure, a cheap plug-in energy monitor reads actual consumption over time, which you can then enter as the watts here.

What about standby power?

Many devices still draw a few watts on standby, and across a houseful of always-on smart-home kit that adds up. If you're costing standby, enter the standby wattage (a monitor will show it) and 24 hours a day. Devices on a switched-off smart plug draw nothing.