SONOFF S31 WiFi Smart Plug with Energy Monitoring, 15A Smart Outlet Socket ETL Certified, Work with Alexa & Google Home Assistant, IFTTT Supporting, 2.4 Ghz Wi-Fi Only 2-Pack

(6 customer reviews)
Operation ModeON-OFF
Current Rating15 Amps
Item Dimensions LxWxH3 x 2 x 1.02 inches
Mounting TypePlug-In Mount
International Protection Rating50
  • [Monitor Energy Consumption]:Keep track of real-time power, current and voltage of your appliances on App.and Measure your appliances’ power consumption for 100-day daily/monthly energy usage data and total electricity cost.
  • [Works with Alexa & Google Home,IFTTT Supporting]: Link ‘eWeLink Smart Home’ skill. You can directly ask Amazon Echo/Echo Dot/Amazon Tap to turn on/off your SONOFF devices.Link ‘eWeLink Smart Home’ on Google Home app, start to voice control your SONOFF devices on Google Home.
  • [Smart Remote Control Plug]: You can remotely/timely control ON/OFF any connected home appliance via APP eWeLink on your smart phone or tablet. No distance/time limitation.
  • [Set time schedules for the lights and home appliances]: You can set countdown/single/repeat timers to auto-turn on/off the WiFi controlled outlet on App. One tap ON/OFF Energy Saving.
  • [Share control of devices to others]: You can simply share control of your home appliances to others so that they can also turn on/off the devices remotely.
SKU: B08GKGS197 Category:
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Features and specification

Brand Smart devices brand

Integration Supported smart home integration

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Interface Smart device connectivity interface

Manufacturer Smart device manufacturer


Voltage (V)

Wattage (W)

Batteries Included?

Batteries Required?

Product Dimensions

‎3 x 2 x 1.02 inches

Mounting Type



Controller Type

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Item Weight

Control Method

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Operation Mode

Connectivity Protocol

Frequently asked question

Does the product contain harmful substances?

Yes. If you eat it, you will most likely have a stomachache.

How long can the product be used?

Until the power company runs out of electricity.

Aren't watts supposed to equal amps x volts?

I measured my freezer. Ewelink shows 122Vrms, 1.71A, 104W. I scoped the line input to see the voltage vs current waveform (volts across a 1.1ohm resistor). Phase delay measures 2.85ms, angle is 62 degrees (cos60=0.5). I checked the current, and both a current clamp and voltage across the 1.1ohm resistor say th… see more I measured my freezer. Ewelink shows 122Vrms, 1.71A, 104W. I scoped the line input to see the voltage vs current waveform (volts across a 1.1ohm resistor). Phase delay measures 2.85ms, angle is 62 degrees (cos60=0.5). I checked the current, and both a current clamp and voltage across the 1.1ohm resistor say the 1.71A trms ewelink value is correct. Finally I checked my PG&E smart meter while turning the freezer on and off -- it showed around 100W difference. Looks to me like ewelink is calculating power correctly for sinusoidal loads.

is it safe to use with a portable ac unit? 14.000 btu

This product is rated for 15 Amps. 15A x 120v = 1800 watts. You should only run a continuous load at around 80% of the rated capacity. 1800w x .8 = 1440w. Most 14,000 btu air conditioners should be around this value, but I would double check the wattage. I wouldn't plug anything else into the socket.

6 reviews for SONOFF S31 WiFi Smart Plug with Energy Monitoring, 15A Smart Outlet Socket ETL Certified, Work with Alexa & Google Home Assistant, IFTTT Supporting, 2.4 Ghz Wi-Fi Only 2-Pack


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  • Anonymous

    S31 Works with Home-Assistant -NO Flashing needed

    I first bought SwitchBot smart plugs thinking they would work with the Core SwitchBot integration with Home-Assistant, extremely disappointed in not only the broken integration, but also the terms of service from a company that has had a lot of recent YouTube praise. Unfortunately, it just shows the known ignorance and total abandonment of values in the name of convenience… Enter HACS and Sonoff, While Sonoff is also doing some data mining it is possible to run the S31 Smart Plugs completely local without the app or the cloud using HACS on Home-Assistant with no fooling with jumpers or fussing with flashing. Several recent HA forum posts and YouTube videos cover the procedure, just look for the most current so you can follow along more easily since the recent changes.
    Also, Stay away from the S40 if you use Home-Assistant. S31 is the way to go.
    Deducted a star for the shady terms of service that are getting all too common with IoT products. Otherwise, it would be 5 stars.

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  • Anonymous

    Pain in the A55 to pair, but finally found a way

    Tried for days to pair and almost returned them. Most only searches so older versions of the app and the app is not intuitive at all. It is very picky with how your wifi is set up. The Name(ssid) and passwords Can Not have any spaces or special characters. This was a challenge because we are not able to change these without have to re setup all our other devices. Some are security cameras that are very difficult to get to (26′ high and 1/4 mile from our router). Our router is only 2.4ghz but the app kept acting as though we were trying to connect to a 5ghz router. Ultimately we had to add a Guest Account named Letters only and set the password with the same restrictions (which makes for a very weak password).
    Once paired…whew, It seems to be working. The app does Not give the level of detail I was hoping for. It only provides total daily power usage or instantaneous usage. I wanted to see what time the refrigerator defrost heater came on, for how long and how much power it used but the app doesn’t do this.
    With all this considered it is a good value and we may even buy more now that we are able to pair them. One star deducted due to the app, not the switch itself. Although, if the devices continues to work well over time without loosing connectivity or failing we will update to full 5 stars.
    We were able to determine the fridge pulls about 1amp/120watts while the compressor is running and a total usage of about 0.9kw over 24hrs. The hair drying on high heat and fan pulls over 13amps/1600watts which is almost the max rating of the device. Be careful not to overload. Only ran for a moment so can’t speak to how long it can handle this level of current draw. Lastly the basic math calculation is not 100% accurate which should be very easy to accomplish. Volts x Amps = Watts. The device measures the amps and the volts and calculates the watts. They were reasonably close but not perfect. See image attached, should be 126 watts.

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  • Anonymous

    Own Over 25 Of Them, Tasmotized And Mostly Happy

    Like many other reviewers, I have purchased this particular switch to install Tasmota on. I use them for energy monitoring, and in some cases their ‘original intent’ – outlet switching, in my home. I buy whatever pack is cheapest per unit at the time, be it 1, 2 or 4 pack versions. They’re all the same in my experience.
    To get them installed with Tasmota, I first tried to solder leads to them. Then I tried to solder pin headers and that was a little bit easier. I’m slightly beyond entry level skill with soldering, but I destroyed at least three units in this learning process. I finally graduated to micro-grabber electrical test clips and have ripped through over two dozen conversions now without incident.
    Let’s be frank. I’d rather Sonoff just offered Tasmota OS from the get-go, or made these over-the-air flashable. I will settle for nothing less than local control and I’m definitely not itching for a ‘new and different cloud solution or app.’ I’d prefer not to hack these devices in the first place and if Sonoff works towards preventing this from a hardware or software standpoint, I will buy no more of them. At the time of this writing (March 2022), this is probably one of the cheapest way to get local energy monitoring and basic 15 amp capable on/off outlet switching.
    I use Home Assistant for my home automation platform. These are fully compatible with their new ‘energy monitoring’ dashboard. This provides me with significant insight into my home’s energy use, especially now that they’re widely distributed to the overwhelming majority of my outlets. I usually capture between 13-18 kilowatt hours per day, the bulk of my usage. To be clear, I use ‘higher grade’ energy monitoring switches in ‘mission critical’ applications (furnace, fridge, etc.), but these are great even for non-mission critical high amp usage scenarios up to 15 amps. I’ve pushed some of mine well up to the limits and haven’t had any major problems or sparks fly.
    Out of a couple dozen, I’ve had one actual device failure. Oddly enough, even with different firmware, different units operate differently on my WiFi. Some stay connected to Wifi 100% of the time, others intermittently connect throughout the day. I don’t lose any granular Home Assistant data because of this, nor are they ever inaccessible and fail to turn on/off. I don’t have a good answer as to why different units behave differently with the same software. Odd behavior, but it doesn’t result in problems. I really can’t complain anyway, I’m using them well outside of the manufacturer’s intended use.
    Build quality is ‘good enough’ but I wish there was a bit more consistency. Since the majority of buyers are intending to hack these, I really wish they wouldn’t cinch down some of the poor-quality screws like they are Shee-Ra or the Hulk. I’ve destroyed way more screws than I’ve wanted, and that’s with the ‘perfect screw removal tool’ which I’ve determined to be a 2.0mm flathead screwdriver. Again, I just wish I could buy a decent quality, super cheap, 15 amp capable smart switch product with the OS of my choice out of the gate.
    I’ve used these to solve VERY REAL problems in my home. From triggering outlets based on other inputs to making serious dents in energy conservation, I believe the $200ish dollars I’ve put into these Sonoff S31 units will eventually pay for themselves. It’s fairly easy for me when I’m paying almost $0.25 per kilowatt hour, others might not have as good of an ROI. If anything, I’ve achieved ‘some level’ of energy usage consciousness. I’ve killed and/or automated quite a few parasitic energy draws I wasn’t even aware of, and have easily increased my automation abilities at the same time.
    It’s important to know that these utilize about 2 watts each, just to function. This might not seem like much, but with two+ dozen of them running 24 hours a day – we’re talking about a ~50 watt constant load just to monitor outlet energy. For me, I’ve killed and automated much more than that, so I’m ‘in the black’ as it were. It’s important, at least for me, to keep tabs on the cost and value of energy monitoring. I’m hoping I can continue to use these to save at least $500 in energy in the next 5 years, and so far, that seems to be a reasonable goal based on how I use them.
    Lastly, I don’t want to get too much into minutia, but you need a fairly robust WiFi network to support the ‘internet of things’ over WiFi. Personally, I utilize multiple networks, including Lutron, Z-Wave, Zigbee and WiFi to get there. Put simply, I don’t use these ‘cheap and ubiquitous’ hacked WiFi devices to service mission critical applications in any way. If a failure would cost me a fair bit of money, I spend more than $10 to capture energy usage and (sometimes) provide switching capabilities.
    +4 stars for being a hackable and very useful device overall. You can debate about that last star, even I waver between 4 and 5 stars. They provide much value for not much dollar and a reasonable +/-2 year path to return on investment for many people that are trying to optimize energy consumption or provide local, automated switching controls.

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  • Anonymous

    Effective at finding power draining appliances

    I bought a single S31 to figure which of my appliances was the most power-draining. What I did is simply use the single S31 power plug to monitor each suspect appliance for 2-3 days. The Android App has a kWh power consumption meter which you can start and stop. I was able to find out that my refrigerator was actually the culprit, using about 2kWh a day.
    I would have given the S31 a 5-star but for the fact that the software app is not the most intuitive to use. But it does the job and the S31 plug itself is only $15.

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  • Anonymous

    A very easy way to add home automation

    Adding new devices can be daunting at first, but once you get the hang of it, it becomes a breeze. The ability to monitor appliance energy consumption is a definite plus, and being able to schedule the ON/OFF times is only second to being able to remotely power on, or turn off anything plugged into the unit.

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  • Anonymous

    Good quality. Works for the purpose. Tool to check device usage.

    I use for dehumidifier, Steamer, Online media box. I use for coffee maker to start 8 am. Surprised it made coffee 12pm lunch time. Too many ads in the app. For 4$ each. And Wi-Fi. CAnt beat the price but not perfect.

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