Use this page to check cable modem electricity consumption for your own cable modem: enter your wattage, hours of use per day and electricity rate, and press Calculate. You see your daily, monthly and yearly cost plus your yearly kWh consumption. Those same results also cover cable modem power consumption.
Your cable modem electricity consumption is tiny on any single day, but the box never takes a night off, so the habit adds up on your energy bill. A typical standalone unit draws 6 to 12 watts, while an all-in-one box often lands between 12 and 25 watts. Below you will find the numbers, the math to turn that wattage into kilowatt-hours, and a few ways to shave the total.
A cable modem converts the signal on your coax line into a data connection your home network can use. It has no screen, no moving parts and no heavy processor, which is why its power draw is far lower than that of a refrigerator or a window air conditioner. The catch is the 24/7 schedule: a device pulling 8 watts for 8,760 hours a year consumes real energy, even though no single hour looks costly. For comparison, see iron electricity consumption.
The table below summarizes what you can expect from common home internet equipment. Treat these as planning ranges, not guarantees, because every unit and firmware build behaves a little differently.
| Equipment | Typical wattage | What drives the draw |
|---|---|---|
| Older standalone cable modem | 5-9 W | Channel bonding, Ethernet port |
| Newer standalone cable modem | 6-12 W | Wider channels, faster hardware |
| Multi-gig cable modem | 9-20 W | 2.5 GbE or 10 GbE interfaces |
| All-in-one unit | 12-25 W | Radios, routing, voice ports |
| Separate modem plus Wi-Fi router | 15-35 W combined | Router performance and attached devices |
Most manufacturers publish a power rating for each model, and independent measurements tend to agree with them. Popular modems from the newest generation report roughly 7 W at rest and a bit more under load, while integrated units from internet providers can pass 20 watts because they also run radios and a routing engine.
A basic standalone modem is the lightest item in the chain. Expect about 5 to 9 watts for an older unit and 6 to 12 watts for a recent one. Its wattage barely changes whether anyone is online or asleep, because most of the draw comes from keeping the connection to the cable plant alive.
A modem/router gateway merges two boxes into one case. With antennas and routing hardware inside, it usually sits between 12 and 25 watts. That sounds worse than a modem alone, but it can still be cheaper than a combined modem and router built from two separate boxes with two power bricks.
If you own a separate wifi router, add its draw to the modem's. A modest wifi router uses 5 to 15 watts, so a modem and router pair commonly totals 15 to 35 watts. Mesh nodes and Ethernet network switches push that higher, since each one adds its own continuous draw to your home network. Check the wifi router label separately from the modem's.
Two modems with the same label can behave differently on your desk. These are the factors that move modem power consumption the most.
The newer cable standard bonds more channels and uses a faster chipset, which is why a DOCSIS 3.1 unit often draws a watt or two more than an older one. A newer DOCSIS generation is more efficient per bit, so the gap narrows as models mature.
Faster Ethernet speed costs electricity. A multi-gig port that negotiates 2.5 or 10 gigabits keeps extra circuitry awake, so these modems sit at the upper end of the range even when nothing is plugged in.
Built-in Wi-Fi is the largest single add-on. Active Wi-Fi radios and telephone ports can double a unit's draw compared with a plain modem. If you already own a better router, switching the wireless off (or choosing a bridge-mode modem) can lower the total. Wi-Fi is optional on many setups. A modem with integrated Wi-Fi is convenient, but it is rarely the thriftiest choice.
Most units rest in a ready state, and the operating state changes little between idle and heavy use. That steady standby power is why busy evenings add only a fraction of a watt, and why unplugging for a long trip saves more than gentle daily habits do.
Listings for the same model can differ by several watts because testers measure at different moments: right after boot, with every port active, or after the unit has settled. A manufacturer's ready-state power number is usually the most representative, and a mid-range plug-in reading is the best tiebreaker.
Your utility bills kilowatt-hours (kWh), not watts, so you need two steps: convert the device's wattage to daily energy, then multiply by the price per unit. For a device that runs all day: Compare with how much electricity does a central air conditioner use.
$$\text{Daily kWh} = \frac{\text{Watts} \times 24}{1{,}000}$$To scale it up, multiply by the days in the period. A year of continuous use equals 8,760 hours, so:
$$\text{Yearly kWh} = \frac{\text{Watts} \times 8{,}760}{1{,}000} \qquad \text{Cost per year} = \text{Yearly kWh} \times \text{Rate per kWh}$$If the label only lists the voltage and amps, multiply them first: \(\text{Watts} = \text{Volts} \times \text{Amps}\). Be careful, though: an AC adapter that says 12V 2A is a ceiling of 24 watts it can deliver, not what the modem actually pulls.
This table runs the formula for three sample loads, with a daily and 30-day view. It uses a sample electricity rate of 18.6 cents per kWh to keep dollar figures comparable across rows.
| Continuous draw | Daily kWh | 30-day kWh | Yearly kWh | Cost at 18.6 cents |
|---|---|---|---|---|
| 8.3 W modem | 0.199 | 5.98 | 72.7 | $13.52 |
| 13.7 W combo unit | 0.329 | 9.86 | 120.0 | $22.32 |
| 21.4 W modem plus router | 0.514 | 15.41 | 187.5 | $34.88 |
Even the heaviest row here is a small slice of a family's yearly usage. The takeaway is relative: the heaviest setup uses roughly two and a half times the electricity of the lightest.
The cost to run a modem depends entirely on where you live. Rates vary widely by state and by season, so use the figure on your own statement instead of the average electricity rate quoted in news stories. You can also check cctv security camera electricity consumption.
Say your modem is rated at 8.3 watts and your provider charges 18.6 cents per kWh. Daily energy is \(8.3 \times 24 \div 1000 = 0.199\) kWh. Over a year that is 72.7 kWh, so the annual cost is about $13.52, and the monthly cost works out to roughly $1.13. Swap in a 13.7-watt combo unit and the same math gives 120.0 kWh, or $22.32 a year.
Because the equipment runs all day, the hours per year figure stays fixed at 8,760. If you do switch it off overnight for eight hours, multiply by 5,840 hours instead, and the kWh drops by a third.
If your plan uses time-of-use pricing, a modem still runs through the expensive evening window, and you cannot shift its schedule the way you can with a dishwasher. The off-peak discount helps only if you can safely switch the equipment off overnight, which is rarely practical for a home with phone service or security cameras.
The label is a starting point; a measurement is the answer. Here is how to get a trustworthy number for your own energy usage.
A plug-in watt meter costs little and settles the question. Plug the modem in through the meter, let it settle for ten minutes, and read the watts. Repeat with your router, then log both numbers to reach an honest electricity usage total for your network.
Run the meter for an hour of quiet time and again during a large download. Both readings should land within a watt of each other, which confirms that traffic hardly matters.
Before swapping equipment, compare the new unit's published ready-state figure with what you measured on the old one. Using the sample loads above, a 13.7 W unit replaced by an 8.3 W modem saves 5.4 W. Run through the formula, that is \(5.4 \times 8760 \div 1000 = 47.3\) kWh a year, or about $8.80 at 18.6 cents per kWh. A gap of only two or three W is worth just $3 to $5 a year, so treat efficiency as a tiebreaker next to speed and reliability.
Log the measured reading with the date and your equipment list. When you add a mesh node or change plans, rerun the yearly kWh formula and see exactly how your total moved over the previous year.
Savings here are modest, but a few habits cost nothing.
Avoid rebooting repeatedly in the hope of saving energy; vampire power from a modem is part of normal operation, and restarts rarely change the total.
Small loads make good candidates for backup power. During a power outage, keeping the modem alive still requires the router, and sometimes the ONT or a mesh system, to be powered too, otherwise your internet connectivity is lost even though the lights on the modem stay green.
Divide the battery's usable watt-hours by your combined load. A 256 Wh portable power station feeding a 21.4-watt setup should deliver about 12 hours on paper, so plan for closer to 9 or 10 hours of battery runtime once conversion losses are counted. A bigger battery lasts proportionally longer, which is why battery capacity matters more than the modem's own draw.
A solar generator pairs a battery with a charge controller and solar panels, so the battery refills during daylight. Because a 21.4-watt load uses about 0.51 kWh a day, even a single 100-watt solar panel in good sun can offset that over a day, and a modest solar generator can carry your internet through a multi-day outage. Pair it with a solar panel rated above your daily need, since cloudy weather cuts output sharply.
Keeping a cable modem running does not give your phone usable Wi-Fi unless the router runs too. Size your power needs around the full chain, from the coax entry point to the last access point, rather than the modem in isolation. During a long outage, turn off devices that do not need the internet, such as a spare mesh node, so the battery lasts longer.
For perspective, a modem's draw is closer to a phone charger or a small LED lamp than to the large appliances that drive a monthly utility bill. Heating, cooling and water heating dominate; your internet gear rarely makes the top ten. Among small appliances and electronics, it is still among the few that run without a break. Even so, the total energy consumption of the whole network, including routers, switches and set-top boxes, is worth tracking if you are trimming a monthly bill. A modem is also a very cheap place to start because the savings do not reduce comfort or connectivity.
Streaming and gaming do not meaningfully change the draw. Your devices use bandwidth, but the modem's efficiency comes from its hardware, not from traffic volume, so heavy use leaves its electricity demand almost flat.
Multiply one modem by the number of broadband households and the energy adds up on a national scale. Every watt trimmed from a cable box is a watt that a power plant does not need to supply, so the environmental argument for efficient equipment is real even though one home saves little. Industry programs now publish ready-state power numbers for modems and gateways for exactly this reason, and efficient designs keep improving the energy picture for the whole internet.
At home, the most practical contribution is to choose efficient equipment when you replace it, avoid leasing a second device you do not need, and keep the load honest by measuring it once. That small effort turns an invisible 24-hour draw into a number you understand.
Yes. It stays in a ready state continuously so the connection to your internet service provider remains open. Expect nearly the same wattage whether the household is awake or asleep.
Usually. It powers radios and a routing engine on top of the modem, so its load is higher, but it can replace a separate router and save the second power brick.
A DSL modem sits in a similar range, while a fiber ONT is often a few watts lighter. Check the label, then confirm with a meter.