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Most US smart plugs are rated 1,800 watts at 15 amps on a 120 volt circuit, which is the full capacity of a standard household outlet. Many budget models are rated lower — 1,200 or 1,500 watts — and some compact designs only 600 to 1,000. The rating is printed on the plug body and in the manual, and it is a hard ceiling rather than a target. For anything running longer than a few minutes, keep the load under 80 percent of the rating, which means about 1,440 watts on an 1,800 watt plug. Space heaters are excluded by most manufacturers regardless of the arithmetic. The same overload rule applies upstream of the plug itself: never run a smart plug off an extension cord or a multi-outlet converter, and keep one heat-producing appliance per outlet.
What ratings do you actually see?
Check the plug rather than assuming. Ratings vary widely within the same brand, and the compact models people buy in multipacks are usually the lowest.
| Rating | Amps at 120 V | Safe continuous load | Typical of |
|---|---|---|---|
| 1,800 W | 15 A | 1,440 W | Full-size and outdoor plugs |
| 1,500 W | 12.5 A | 1,200 W | Mid-range indoor plugs |
| 1,200 W | 10 A | 960 W | Common budget rating |
| 1,000 W | 8.3 A | 800 W | Compact multipack plugs |
| 600 W | 5 A | 480 W | Mini plugs and some smart outlets |
The 80 percent guidance comes from the way the National Electrical Code treats continuous loads — anything drawing for three hours or more is limited to 80 percent of the circuit rating. Applying the same margin to a switching device with mechanical relay contacts is straightforward good practice.
What do common appliances actually draw?
Nameplate figures, which you will also find printed on the appliance. The right-hand column is the practical verdict for a typical 1,800 watt plug.
| Appliance | Typical draw | On a smart plug? |
|---|---|---|
| LED lamp | 5–15 W | Yes |
| Box or tower fan | 40–100 W | Yes |
| Dehumidifier | 300–700 W | Yes |
| Slow cooker | 200–300 W | Yes |
| Coffee maker | 800–1,200 W | Yes, if the plug is 1,800 W |
| Window air conditioner | 500–1,500 W | Check the plug rating and the startup surge |
| Portable space heater | 1,500 W | No — excluded by most manufacturers |
| Toaster oven | 1,200–1,800 W | No |
| Hair dryer | 1,500–1,875 W | No |
| Electric kettle | 1,500 W | No |
| Refrigerator | 100–250 W running | No — not because of watts, but because an accidental off spoils food |
Why do motors need extra headroom?
Because a motor draws an inrush current at startup that is commonly three to seven times its running current, for a fraction of a second. A window air conditioner listed at 900 running watts may pull several thousand for the first instant of every compressor cycle, and that surge is what welds relay contacts over time. The same applies to pumps, compressors, shop vacuums and power tools.
If you must switch a motor load, use a plug rated 1,800 watts, keep the running load well under 1,000 watts, and prefer a model that publishes a resistive and an inductive rating separately — the inductive figure is the honest one for motors. Where a plug simply is not the right tool, a hardwired smart switch or relay installed by an electrician handles the load properly; the difference between the two device types is set out in smart plug vs smart switch. If a plug or the outlet behind it ever feels warm, discolors, or you notice flickering lights or a burning smell, that's a sign of an overloaded circuit — stop using it and call an electrician rather than just downgrading the appliance.
One last check: buy plugs carrying a recognized safety certification mark, because this category attracts uncertified imports where the printed rating is aspirational. The models owners rate highest for build quality, accurate metering and honest ratings are in our smart plug picks, and the sensible jobs for them are listed in what you can do with a smart plug.
We never buy, install or physically handle the products we rank. Every recommendation comes from aggregated owner reviews, star ratings, review volume and published expert consensus — see how we rank.
More from this hub: Smart Home & Security · Smart plug standby draw · How to set up smart plugs · Best smart plug · How we rank