How to read an appliance label for watts
Updated
Find the rating label
Look for a small plate or sticker with the electrical rating. On most appliances it sits on the back, on the bottom or inside a door. On a laptop, a CPAP or a phone charger, read the power brick, not the device.
The plate states what the appliance needs from the outlet: in the US, 120 V at 60 Hz for nearly everything you would run from a portable power station. A plate that says 240 V is a different case. 8 of the 54 stations in the data set supply 240 V on their own, and the calculator checks that for you.
Why your label beats a typical value
Each appliance type in the data set carries a low, a typical and a high running figure, because models differ. The calculator starts from the typical one. A few examples show how wide the range can be:
| Appliance | Low | Typical | High |
|---|---|---|---|
| TV, 55 inch LED (LCD) | 70 W | 82 W | 102 W |
| Laptop (while charging) | 5 W | 65 W | 100 W |
| CPAP machine (no humidifier) | 7 W | 11 W | 20 W |
| Refrigerator (modern, full size) | 150 W | 275 W | 400 W |
| Electric space heater (1,500 W) | 750 W | 1,500 W | 1,500 W |
Across all 79 types, the high figure is 1.7 times the low one at the median. For a load near a station's limit, that spread can decide between Enough and Cannot power it, and the label settles it.
Watts printed on the label
Many labels give the power directly, marked W. That figure is the rated input power. Enter it as the running watts. An appliance with settings often lists the highest one: a heater rated 1,500 W may also show 750 W for its low setting, and you should enter the setting you plan to use.
A microwave is a common trap. The power in its name or on the front panel is cooking power, and the rating plate lists the input power, which is what a power station has to supply. In the data set, the microwave oven (1,000 W cooking power) draws 1,500 W to 1,800 W at the plug.
Only volts and amps
When the plate shows volts (V) and amps (A) but no watts, multiply them: watts = volts × amps. A plate reading 120 V and 1.5 A means 180 W. On AC appliances the product can come out above the real draw, never below it, so any error falls on the safe side for sizing.
Power bricks and chargers
A brick lists an input and an output. The output line gives what the device can take: 20 V and 3.25 A is 20 × 3.25 = 65 W. The brick loses a little energy on top of that, so round up and enter 70 W. The input line is a rating for the whole voltage range the brick accepts, and multiplying it by 120 V gives a figure well above the usual draw.
The EnergyGuide label
The yellow EnergyGuide label shows how much energy an appliance uses and how that compares with similar models. The Federal Trade Commission lists the products that carry it, among them refrigerators, freezers, televisions, ceiling fans and room and portable air conditioners. Under the labeling rule, 16 CFR Part 305, the label states the estimated yearly energy use, for electric appliances in kilowatt hours per year.
The yearly figure assumes typical use, so read it as an estimate. To turn it into watt hours a day, divide by 365 and multiply by 1,000.
- Label
- 450 kWh a year
- Per day
- 450 ÷ 365 = 1.23 kWh
- In watt hours
- 1.23 × 1,000 = 1,233 Wh a day
The calculator already counts refrigerators and freezers by their daily energy. If you enter your fridge's label watts instead, it counts those watts for every hour you enter, as if the compressor never rested. Set the hours to the time the compressor runs: daily watt hours ÷ running watts. With 1,233 Wh a day and 150 W, that is 1,233 ÷ 150 = 8.2 hours.
Starting watts are seldom on the label
Most rating plates give running figures only. The appliance pages list typical starting watts where a source publishes them, and starting watts explained covers what to do when none is published.
Enter it in the calculator
- Add the appliance in the runtime calculator.
- Choose Use the watts on your label under it and type the running watts.
- Set the hours a day you plan to run it.
- For something the list does not have, add it under Your own appliance with its running watts and, for a motor, its starting watts.
The address of the calculator page holds your list, label watts included, so a copied link opens the same result on another device.
Sources
- How To Use the EnergyGuide Label To Shop for Home Appliances, Federal Trade Commission, checked October 6, 2026.
- 16 CFR Part 305, Energy and Water Use Labeling for Consumer Products, Electronic Code of Federal Regulations, checked October 6, 2026.
- Power station and appliance figures: the Enough Watts data set, each record with its own sources and dates.