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How Much Power Does a Phone or Tablet Use While Charging?
Jan 28, 2016MobileComments (4)
The amount of power your mobile device consumes while charging depends on the amperage rate of your charger. This should be listed on the plug-in part of the charger in very small print. For phones it is usually around 1.2A at 5.0V. For tablets it is usually around 2.0A at 5.0V. USB charging usually delivers 500mA (0.5A) at 5.0V.
Higher amps means a faster charge and more power consumption. Most devices use 5 volts, so you can calculate how much power in watts is being used with the simple equation Volts * Amps = Watts:
As you can see, the amount of power being used is roughly similar to an LED light bulb, or maybe a small fan.
Let's say you charge your device for 2 hours every other day at 1.2A. That means you'll spend 365 hours charging your device in a year. At 6 watts, that's 2190 watt-hours, or 2.19 kilowatt-hours (kWh). If your utility company charges 12 cents per kWh (rough US average), then that means it costs you 26 cents per year to keep your device charged up.
The actual power usage varies a bit. Using a Kill-A-Watt I found that my Nexus 5 with factory LG charger (1.2A at 5.0V) used between 6.5 to 7.7 watts depending on if the screen was on or off, and what I was doing with it while it was charging.
Higher amps means a faster charge and more power consumption. Most devices use 5 volts, so you can calculate how much power in watts is being used with the simple equation Volts * Amps = Watts:
| Volts | Amps | Watts |
|---|---|---|
| 5.0V | 0.5A | 2.5 |
| 5.0V | 1.0A | 5.0 |
| 5.0V | 1.2A | 6.0 |
| 5.0V | 2.0A | 10.0 |
| 5.0V | 2.1A | 10.5 |
As you can see, the amount of power being used is roughly similar to an LED light bulb, or maybe a small fan.
How Much It Costs
Let's say you charge your device for 2 hours every other day at 1.2A. That means you'll spend 365 hours charging your device in a year. At 6 watts, that's 2190 watt-hours, or 2.19 kilowatt-hours (kWh). If your utility company charges 12 cents per kWh (rough US average), then that means it costs you 26 cents per year to keep your device charged up.
Inconsistencies
The actual power usage varies a bit. Using a Kill-A-Watt I found that my Nexus 5 with factory LG charger (1.2A at 5.0V) used between 6.5 to 7.7 watts depending on if the screen was on or off, and what I was doing with it while it was charging.