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How many watts does a laptop use?

A typical laptop uses 35–245 watts when running and draws 0.29–2 amps at 120 volts.

Laptop watts, amps and circuit

Typical power use of a laptop
Running watts35–245 W
Voltage120 V
Running amps0.29–2 A
Circuitstandard 120 V outlet

Also called: laptop charger, macbook, macbook pro, macbook charger, chromebook charger.

Laptop watts by size and type

Running and starting watts of laptop types
Size or typeRunning watts, WVolts, VAmps, AStarting watts, W
Laptop35–2451200.29–2—
Chromebook, charger rating45–651200.38–0.54—
13-inch MacBook Air, charger rating35–701200.29–0.58—
16-inch MacBook Pro, charger rating1401201.2—
Gaming laptop, charger rating135–2451201.1–2—
0100200300Watts, WSize or typeLaptopLaptop, Running watts: 35–24535–245Chromebook, chargerratingChromebook, charger rating, Running watts: 45–6545–6513-inch MacBookAir, charger rating13-inch MacBook Air, charger rating, Running watts: 35–7035–7016-inch MacBookPro, charger rating16-inch MacBook Pro, charger rating, Running watts: 140140Gaming laptop,charger ratingGaming laptop, charger rating, Running watts: 135–245135–245050100150200250Watts, WSize or typeLaptopLaptop, Running watts: 35–24535–245Chromebook, charger ratingChromebook, charger rating, Running watts: 45–6545–6513-inch MacBook Air, chargerrating13-inch MacBook Air, charger rating, Running watts: 35–7035–7016-inch MacBook Pro, chargerrating16-inch MacBook Pro, charger rating, Running watts: 140140Gaming laptop, charger ratingGaming laptop, charger rating, Running watts: 135–245135–245
Watts of laptop types. The lighter part of a bar is the upper end of the typical range.

What size generator runs a laptop?

A laptop needs a generator that supplies at least 245 running watts. A 2,000 W generator covers it with its running rating alone; add the watts of anything else you run at the same time.

How long a portable power station runs a laptop

Runtime of a laptop on a portable power station, at 85% inverter efficiency
Battery capacity, WhAt 245 W, hAt 35 W, h
5001.712.1
1,0003.524.3
2,0006.948.6
3,60012.587.4

A 500 Wh portable power station runs a laptop drawing 245 W for about 1.7 hours at 85% inverter efficiency. Runtime = capacity × 85% ÷ watts; the 85% efficiency is an assumption. The power station's AC output must be at least 245 W.

What it costs to run a laptop

Running a laptop at 140 W, the middle of its 35–245 W range, for one hour a day uses 51.1 kWh a year. That costs about $9.20 a year at $0.18 per kWh, the US average residential price for August 2026.

W
h
$/kWh

Your bill's total ÷ kWh used. 0.18 is the US residential average.

Result
$0.77 / month
Per day
$0.03
Per year
$9.20
Energy per day
0.14 kWh
Energy per month
4.3 kWh

How it is calculated

  1. kWh per day = 140 W × 1 h ÷ 1,000 = 0.14
  2. Per month = 0.14 kWh × 30.4 days × $0.18 = $0.77

What affects laptop power use

The charger rating is the most a laptop can draw; it uses close to that only while charging a low battery under heavy load. Once the battery is full and the work is light, the draw drops to a fraction of the rating.

How the amps are calculated

Amps = watts ÷ volts. For 245 W at 120 V that is 2 A. The 35–245 W range covers typical models; the nameplate on a laptop gives the exact figure.

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