Electricity

Standby power: what always-on devices actually cost

A few watts sounds like nothing until you multiply it by 8,765.8 hours.

Published 23 August 2026 · Published by SnapEnergyLab. Methodology and default assumptions are documented separately.

A living room in the blue hour lit by a floor lamp, where switched-off electronics still show small standby indicator lights

Quick answer

Every watt left running permanently costs 8.766 kWh a year. That is the whole calculation, and it is why the honest answer to “should I unplug my chargers?” is no, while the honest answer to “should I deal with the set-top box?” is yes.

Modern regulated standby is a fraction of a watt. What still costs real money is always-on equipment: recorders, consoles in instant-on mode, network gear and anything with a compressor or fan that never fully stops.

How to read the numbersSite defaultCalculated resultIllustrative model

Hours in a year: 8,765.8; Site default
1 W left on all year: 8.766 kWh; Calculated result
At 0.30 per kWh: ≈ 2.63 /yr; Calculated result

The only formula you need

annual energy (kWh) = continuous power (W) × 8,765.8 ÷ 1000
annual cost = annual energy (kWh) × price per kWh
shortcut = watts × 8.766 = kWh per year

8,765.8 is the number of hours in an average calendar year (365.24 days, leap years included) — the same convention every calculator on this site uses. The shortcut is that figure divided by 1,000.

Exact relationship for a constant draw over 8,765.8 hours; no assumption is involved beyond the device never switching off. Cost depends on your own price per kWh.

Show the plotted values

Continuous draw	Annual energy (kWh)
1 W	8.8
2 W	17.5
5 W	43.8
10 W	87.7
15 W	131.5
20 W	175.3
30 W	263
40 W	350.6
50 W	438.3

What is actually worth switching off

The ranges below are typical measured values for equipment sold in the last decade. Yours may differ, and the only way to know is a plug-in power meter — but the ordering is stable enough to act on.

Typical always-on power draw and annual consumption by device
Device	Typical draw	Per year	Verdict
Set-top box / DVR (always recording)	12–20 W	105–175 kWh	Worth addressing — often the largest single standby load in the house.
Games console in instant-on mode	10–15 W	88–131 kWh	Worth addressing — switching to energy-saving mode removes most of it.
Desktop PC asleep with peripherals	5–10 W	44–88 kWh	Worth addressing with a switched strip.
Broadband router	6–12 W	53–105 kWh	Real, but rarely worth switching off in practice.
Television in standby	0.3–1 W	3–9 kWh	Not worth unplugging.
Phone charger, nothing attached	0.05–0.3 W	0.4–3 kWh	Not worth unplugging.
Microwave clock display	1–3 W	9–26 kWh	Marginal.

Worked example: the whole standby stack

Set-top box, instant-on15 WIllustrative model
Games console, instant-on12 WIllustrative model
Router and mesh node14 WIllustrative model
Miscellaneous standby (8 devices)≈ 4 W totalIllustrative model
Continuous total45 WCalculated result
Annual energy45 × 8.766 = 394 kWhCalculated result
Annual cost at 0.30394 × 0.30 = 118Calculated result

Realistically removable share≈ 240 kWh/yr

Measure before you optimise

A plug-in energy meter costs less than a month of the consumption it will find. Leave it on a device for 24 hours rather than reading instantaneous watts — a recorder idling at 12 W may spike far higher while indexing, and a printer asleep at 2 W may wake hourly.

For a whole-house figure, the overnight meter-reading method gives you the true always-on load including things you cannot easily plug a meter into: ventilation, doorbell transformers, boiler controls, alarm systems.

Price your own standby load

Enter the measured watts and 24 hours a day. The calculator returns the annual figure at your rate, which is the number worth comparing against the inconvenience of switching something off.

Open the electricity cost calculator

Assumptions and limitations

Device draw ranges are typical published and measured values, not measurements of your equipment. Actual standby varies by model, firmware and network activity.
Network-connected standby fluctuates: a device that idles at 2 W may average considerably more if it wakes to sync.
In a heated home during the heating season, part of a standby device's energy displaces heating and the net cost is lower. In a cooled home in summer, the net cost is higher.

Sources

Standby power and low power modes — International Energy Agency (4E EDNA)
Supports: Standby and network-connected standby consumption in households, and its share of residential electricity.
Ecodesign regulation 2023/826 on standby and off mode — European Commission
Supports: Regulated maximum standby power limits for electrical and electronic household equipment.