How many watts does a phone charger use?

A phone charger draws 5–45 watts while running, which is 0.04–0.38 amps on a 120 V circuit.

Phone charger watts, amps and circuit

Typical power use of a phone charger
Running watts	5–45 W
Voltage	120 V
Running amps	0.04–0.38 A
Circuit	standard 120 V outlet

Also called: iphone charger, cell phone charger, fast charger, usb charger.

Phone charger watts by size and type

Running and starting watts of phone charger types
Size or type	Running watts, W	Volts, V	Amps, A	Starting watts, W
Phone charger	5–45	120	0.04–0.38	—
Basic USB charger	5–12	120	0.04–0.1	—
USB-C fast charger	18–30	120	0.15–0.25	—
High-power USB-C charger	30–45	120	0.25–0.38	—

Watts of phone charger types. The lighter part of a bar is the upper end of the typical range.

How long a portable power station runs a phone charger

Runtime of a phone charger on a portable power station, at 85% inverter efficiency
Battery capacity, Wh	At 45 W, h	At 5 W, h
500	9.4	85
1,000	18.9	170
2,000	37.8	340
3,600	68	612

A 500 Wh portable power station runs a phone charger drawing 45 W for about 9.4 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 45 W.

What it costs to run a phone charger

Running a phone charger at 25 W, the middle of its 5–45 W range, for one hour a day uses 9.1 kWh a year. That costs about $1.64 a year at $0.18 per kWh, the US average residential price for August 2026.

Power

Use per day

Electricity price

$/kWh

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

Result

$0.14 / month

Per day: $0.00
Per year: $1.64
Energy per day: 0.03 kWh
Energy per month: 0.8 kWh

How it is calculated

kWh per day = 25 W × 1 h ÷ 1,000 = 0.025
Per month = 0.025 kWh × 30.4 days × $0.18 = $0.14

What affects phone charger power use

The rating on the charger is its maximum output. A phone draws close to it only while the battery is low, then slows down as it fills. The rows are adapter ratings from Apple and Samsung, not measured draw.

How the amps are calculated

Amps = watts ÷ volts. For 45 W at 120 V that is 0.38 A. The 5–45 W range covers typical models; the nameplate on a phone charger gives the exact figure.