What a laptop actually draws
The number on the charging brick is not the number on your meter. A 65 W or 96 W USB-C charger states what it is capable of delivering, and it only delivers that much while the battery is genuinely charging — which is a fraction of the day. Once the battery is full, the machine draws only what it needs to run, and a laptop browsing the web, writing email or sitting in a video call settles at 10 to 25 W.
Averaged across a working day, DOE lists 50 W for a laptop, and DTE's chart puts one at 100 watt-hours per operating block. Fifty watts is the figure used here: high enough to cover charging periods and demanding tasks, low enough to reflect how much of a laptop's life is spent idling with a dimmed screen.
Two exceptions push the number up. Gaming laptops and mobile workstations with discrete graphics run 90 to 200 W under load, which is why they ship with bricks the size of a paperback. And any laptop draws near its charger's ceiling for the first stretch after being plugged in flat.
The headline comparison is the one worth remembering: a laptop uses roughly a third the electricity of an equivalent desktop. That is not a marketing claim; it falls out of the hardware. Laptops are engineered around battery life, so every component is chosen for efficiency in a way desktop parts never had to be.
What that costs, worked through
Watts × hours ÷ 1,000 = kWh per day. For a laptop: 50 W × 6 hours = 300 watt-hours, which is 0.3 kWh a day. Over a 30.4-day month that is 9.1 kWh, and at the US average rate of 18.44 cents per kWh, 9.1 × $0.1844 is about $1.68 a month — roughly $20.14 a year, or a little over five cents a day.
Across the range: a small ultraportable averaging 20 W costs about 3.6 kWh a month, roughly 67 cents. A larger machine at 100 W costs 18.2 kWh, about $3.36. A gaming laptop genuinely held at 200 W for six hours would reach 36.5 kWh a month, about $6.73 — still under what a single desktop tower typically costs to run.
Round-the-clock operation, which is common with laptops used as always-on machines, works out to 50 W × 24 hours = 1.2 kWh a day, 36.5 kWh a month, about $6.73 a month or $81 a year. The lid-closed sleep state is about 2 W, or 1.46 kWh a month — roughly 27 cents a month and $3.23 a year.
Put differently: charging a laptop for a full year costs about what running a clothes dryer for four days costs. For a household trying to find real money on a bill, this is not the appliance. Check where the money actually goes with the appliance energy cost calculator.
What makes the number move
Laptop consumption varies more within a single machine over a day than it does between comparable models. The drivers, in rough order of size:
- Screen brightness. The display can account for 30 to 50 percent of total system power. A panel at full brightness in a bright office is a materially different appliance from the same panel at 40 percent.
- Discrete graphics. A gaming or workstation laptop with a dedicated GPU runs 90 to 200 W under load, several times a thin-and-light machine.
- Whether the battery is charging. The one period when a laptop genuinely approaches its charger's rating. A machine plugged in at 5 percent is a different load from the same machine at 100 percent.
- Screen size. A 17-inch panel costs more to light than a 13-inch one, all else equal, and larger machines tend to carry more capable, thirstier chips.
- Workload. Video calls, compiling, exporting video and gaming all engage the processor and fans; reading a document does not.
What barely registers: battery age, whether you use the manufacturer's charger or a compatible one of the same rating, and most of the tweaking people do in operating-system power menus. Chip generation matters, but not in a way you can control after purchase.
One genuine seasonal effect worth knowing: a laptop kept somewhere hot will run its fans harder and its chips hotter, which nudges consumption up slightly. It is a small term, not a reason to act.
Whether it is worth doing anything about
At $1.68 a month, honesty requires saying that nothing you do to a laptop will show up on your bill. A page that promised otherwise would be selling you something.
That said, there is one lever that is both effective and free: screen brightness. Because the display is 30 to 50 percent of total system power, dimming it beats any CPU power-plan tweak you can make. It also extends battery life on the move, which is the reason most people will actually do it. Every other software-side adjustment — switching between balanced and power-saver profiles, disabling background sync, killing startup items — is trivial by comparison.
The second is leaving the defaults alone. ENERGY STAR certified machines ship with the display sleeping after 15 minutes and the system after 30. Disabling those settings because a screen dimmed during a meeting is the most common way people quietly triple a laptop's daily consumption.
Where a laptop does matter is as a replacement. If you are choosing between a desktop and a laptop for the same work, the laptop uses roughly a third the electricity — a difference of about $40 a year at average rates, and more if the desktop would have carried a discrete graphics card. That is a purchase decision, made once, that outweighs every setting on this page combined.
Do not unplug the charger to save money. Left in the wall with nothing attached it draws a fraction of a watt, worth cents a year — the appliance directory shows where that attention is better spent.
How it compares with everything else you plug in
At 9.1 kWh a month, a laptop sits near the bottom of the household table. It matches an LED television exactly at 9.1 kWh, comes in just below a dishwasher at 10.9 kWh, slightly under a toaster oven at 9.3 kWh, and above a WiFi router at 5.8 kWh and a vacuum cleaner at 5.0 kWh.
It uses a third of what a desktop uses at 27.4 kWh, a quarter of a refrigerator's 36.5 kWh, and about one-sixth of an electric dryer's 54.7 kWh. Against a window air conditioner at 218.9 kWh in season, or an electric water heater at 232.6 kWh, it is not in the same conversation.
The comparison that lands hardest is with lighting. A single 60 W incandescent bulb burning three hours a day uses 5.5 kWh a month — more than half a laptop's entire consumption, for one bulb. Six of those bulbs cost more to run than the computer they light.
The general lesson: devices that feel technological attract attention out of proportion to what they cost, while heating anything — water, air, food, clothes — quietly dominates the bill. If your statement has jumped, the laptop is not why. Work through why your electric bill is so high and start with the heating loads.
Frequently asked questions
How many watts does a laptop use?
About 50 watts on average, which is the figure DOE lists, with real draw ranging from roughly 20 W for a small ultraportable to 100 W for a large machine. Gaming laptops and mobile workstations are the exception at 90 to 200 W under load. Do not use the charger's rating as your estimate: a 65 W or 96 W USB-C brick states what it can deliver, and it only delivers that while the battery is actively charging. Once topped off, a laptop browsing the web settles around 10 to 25 W.
How much does it cost to charge a laptop?
About $1.68 a month, or roughly $20 a year, at the US average rate of 18.44 cents per kWh. The arithmetic: 50 watts for six hours a day is 0.3 kWh, which is 9.1 kWh over a 30.4-day month, times $0.1844. A single full charge costs a fraction of a cent to a couple of cents depending on battery size. Left plugged in and running 24 hours a day the same machine reaches about $6.73 a month. There is no version of this that becomes a significant line on a bill.
Does a laptop use less electricity than a desktop?
Yes, by roughly a factor of three for equivalent work — 9.1 kWh a month against 27.4 kWh. The reason is design intent: laptop components are chosen to preserve battery life, so the processor, display and storage are all specified for efficiency in a way desktop parts never had to be. At average rates that is a difference of about $40 a year, and more if the desktop would have carried a discrete graphics card. It is the only decision in this category that changes the number meaningfully.
Should I leave my laptop plugged in all the time?
From an electricity standpoint it makes little difference. A laptop that is plugged in and idle draws what it needs to run, not the charger's full rating, and a fully charged battery stops accepting power. Leaving it plugged in and awake around the clock costs about $6.73 a month against $1.68 for six hours a day — so the cost is in staying awake, not in staying plugged in. Let the system sleep after 30 minutes, which is the ENERGY STAR default, and the question mostly answers itself.