How many watts does a phone / tablet charger use?
Updated
Running watts
20 W
Starting watts
20 W
Energy per day
60 Wh
A phone / tablet charger typically draws about 20 watts while running. At about 3 h of use a day, that is roughly 60 Wh per day. These are typical values from generator wattage charts: the label on your own appliance (or its EnergyGuide sticker) gives the exact figure.
What size generator do I need for a phone / tablet charger?
Plan for at least 24 W: 20 W to get through the start-up surge, plus a 20% margin so the generator never runs flat out. Of the common sizes, a 2,000 W generator is the smallest that fits.
| Generator | Can it run a phone / tablet charger? |
|---|---|
| 2,000 W | Yes |
| 3,500 W | Yes |
| 5,000 W | Yes |
| 7,500 W | Yes |
| 10,000 W | Yes |
| 15,000 W | Yes |
How long will a power station run a phone / tablet charger?
Running continuously at 20 W, assuming 85% of the battery is usable. The station's AC output must also handle the 20 W start-up surge.
| Battery capacity | Runtime |
|---|---|
| 1,000 Wh | about 43 h |
| 2,000 Wh | about 3.5 days |
| 3,600 Wh | about 6.4 days |
Running more than one appliance?
Starting surges don't add up the way running watts do. Pick everything you want to power to get your real number.
Open the CPAP Battery Backup CalculatorFrequently asked questions
What size generator do I need to run a phone / tablet charger?
At least 24 W: 20 W to cover the start-up surge, plus a 20% safety margin.
Can a 2,000 watt generator run a phone / tablet charger?
Yes. 2,000 W covers its 20 W starting surge with room to spare.
Can a 3,500 watt generator run a phone / tablet charger?
Yes. 3,500 W covers its 20 W starting surge with room to spare.
How long will a 1,000 Wh power station run a phone / tablet charger?
About 43 h, assuming 85% usable capacity, as long as the station's AC output is rated for 20 W of surge.
Never run a generator indoors or in a garage: see the CPSC safety guide.