The short answer
For equipment running continuously, divide its average wall-input watts by 1,000 and multiply by 24 hours, days and your tariff. Include a separate modem, fibre terminal and mesh nodes if they are outside the reading. Adapter output capacity and declared idle test power are not measurements of your complete network.
Use the standby & always-on costs calculatorOn this page
Start with the equipment connected to your sockets
The cost of a home network can include a combined modem-router, a separate modem or fibre terminal, Ethernet switches and additional Wi-Fi access points. A mesh system with three powered units needs a boundary covering all three, unless one measurement already includes them together.
Write down each powered unit and whether it is already included in another reading. Add those units in the standby and always-on calculator. Use 24 hours only for equipment you expect to operate all day. Networking equipment maintaining service is doing useful work even when no one is actively browsing.
A declared router figure is a starting point
TP-Link’s 2024 US Small Network Equipment Voluntary Agreement disclosure lists 6.50 W idle power for Archer AX55 in the configuration stated in its table. This is an attributed manufacturer test disclosure, checked on 14 October 2026. It is not our measurement, a maximum-power value, or a reading for every router sold under another regional configuration.
Holding that stated idle value constant gives the following modeled illustration:
6.50 ÷ 1,000 × 24 × 365 = 56.94 kWh/year
At an independently assumed $0.20/kWh, cost would be $11.39/year. Real use can differ from a declared idle configuration. Check model version, connected ports and enabled radios before reusing a declaration.
Edit the declared-idle arithmetic in the electricity calculator. Review the US manufacturer source and replace the tariff with your own; opening this example does not certify that 6.50 W represents your device.
A whole-network example
Suppose a combined set of network equipment averages an illustrative 15 W at the wall over a representative period. Repeated continuously across 365 days:
| Step | Result |
|---|---|
| 15 W ÷ 1,000 × 24 hours | 0.36 kWh/day |
| 0.36 × 365 days | 131.4 kWh/year |
| 131.4 × £0.28/kWh | £36.79/year |
This is a hypothetical total, not a typical network or a second figure for the Archer AX55. Adding two further units at an assumed 5 W each would add 87.6 kWh/year, costing £24.53 at the same rate, if they were not already included. Quantity matters; do not count a three-unit measurement as three times that measurement.
Why the adapter label can overstate ordinary consumption
An adapter marked 12 V, 2 A output has a stated output capacity of 24 W. That arithmetic does not establish that the router continuously takes 24 W from the socket. It also describes a different boundary from AC wall-input power, where conversion losses occur.
Use actual accumulated wall kWh for your routine where possible. A single live reading can miss variation. The measurement guide explains counter subtraction and complete-day sampling. Keep other loads off the measurement boundary, and retain the model and network settings in the journal.
Does switching it off overnight save the full amount?
If an illustrative constant 15 W network were genuinely off for eight hours on each of 365 days, the arithmetic reduction would be 43.8 kWh, or £12.26 at £0.28/kWh, before any different behavior during other hours. Disabling only Wi-Fi is a different change: the modem, routing and wired network may still operate, so it does not justify assuming zero watts.
Check which services need a connection before scheduling power changes. BT’s Digital Voice guidance, for example, states that the hub must have power to make calls. Consult your own provider and equipment instructions; UK service behavior is not automatically evidence about a US cable modem or an EU fibre installation. Keep any phone, alarm or remote-access dependency in the decision.
Compare a setting change fairly
Repeat a complete-day sample with the same equipment boundary before and after the change. Record connected nodes, radios, schedule and unusual downloads. Compare like-for-like observations in the journal and describe any estimated annual saving as a projection.
Then add the network once to the household planner or check it against billed kWh. A router estimate alone cannot explain the rest of an electricity bill.
Price separate operating states
Choose “Separate active, idle and standby modes” in the electricity calculator. Record average input watts, daily hours and a source or assumption for each state. The hours must total no more than 24; unassigned time remains excluded. A complete-day measurement is an alternative and must not be added to overlapping mode estimates. Follow a reproducible mode example before applying your own tariff and use days.