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How Much Does It Cost to Run a Cable or Fiber Modem in the UK? (2026)
A modem runs all day at 5 to 15 watts. Combined with a separate router the pair uses around 15 to 25 watts continuously, roughly 150 to 200 kWh a year.
A typical cable or fiber modem (8 W) costs £0.002 per hour, or about £1.50 per month at 24 hours a day in United Kingdom. Cheap to run
| Wattage | Per hour | Per day | Per month | Per year |
|---|---|---|---|---|
| Low (5 W) | £0.001 | £0.031 | £0.94 | £11.39 |
| Typical (8 W) | £0.002 | £0.050 | £1.50 | £18.22 |
| High (15 W) | £0.004 | £0.094 | £2.81 | £34.16 |
Formula: watts ÷ 1000 × hours × price per kWh. Typical use is 24 h/day ≈ 70 kWh per year.
In the UK, with electricity at £0.26 per kWh (source: Ofgem price cap 1 Jul–30 Sep 2026, 2026-07), a typical cable or fiber modem costs £0.002 per hour and about £18.22 per year at 24 hours a day. Each £1.00 of electricity buys roughly 480.8 hours of use.
How to lower the cost of running a cable or fiber modem
- Replace a separate modem and router with a combined gateway to halve the draw.
- Do not turn it off at night. Reconnection delays are rarely worth the small saving.
- Retire old network gear. Older units often use double the power of current ones.
Frequently asked questions
How much electricity does a modem use per month?
Around 6 kWh a month at 8 watts continuous.
Is it worth turning off the modem at night?
It saves about 2 to 3 kWh a month. Most people find it not worth the hassle.
Do fiber ONTs use less power than cable modems?
Usually a little less, typically 5 to 8 watts.
Cost by region
- United States (average)
- California
- Texas
- New York
- Florida
- Canada (average)
- United Kingdom
- Germany
- France
- Australia
- India