SONOFF S40 Smart Plug (4-Pack) Review: Budget Energy Monitoring Done Right
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Most smart plugs just let you flip something on or off from your phone. The SONOFF S40 4-pack does that too, but it also tells you what that "on" is actually costing you — in real wattage, over time, per outlet. For anyone tired of guessing which appliance is quietly inflating the electric bill, that's the more useful feature.
What It Is
The SONOFF S40 is a Wi-Fi smart plug that fits a standard outlet and lets you control whatever's plugged into it from your phone, a voice assistant, or a schedule. What separates it from bare-bones smart plugs is built-in energy monitoring — it tracks wattage and usage over time, so you're seeing actual consumption rather than just toggling things on and off. This listing bundles four units, which brings the per-plug cost down compared to buying singles.
Who It's For
This is a solid pick for anyone setting up their first few smart outlets without a big upfront investment. It works for renters and homeowners alike, since there's no wiring involved — just plug it in and pair it with an app. It's also a good match for anyone trying to identify which appliances are running up the electric bill: window AC units, older fridges, space heaters, and always-on electronics are common culprits. If all you want is four dumb outlets that respond to a schedule, cheaper options exist — but if you want the data behind your energy use, that's where the S40 earns its keep.
Key Features and Specs
- 4-pack format — covers multiple rooms or devices in one purchase, at a lower per-unit cost than buying single smart plugs
- Real-time energy monitoring — tracks wattage, voltage, and cumulative usage per plug
- Wi-Fi connectivity — no separate hub required, controlled through SONOFF's eWeLink app
- Remote control and scheduling — turn devices on/off from anywhere, set timers, or build routines
- Voice assistant compatibility — works with the major smart home ecosystems for hands-free control
- Compact design — built to avoid blocking the adjacent outlet on standard two-gang wall plates
Pros
- Energy monitoring at this price point is genuinely useful and not always found on comparably priced plugs
- Buying four at once outfits a room or two without repeat shipping costs and packaging waste
- Straightforward setup through the eWeLink app, with no smart hub purchase required
- Good entry point for anyone experimenting with home automation without committing to a pricier ecosystem
Cons
- Physical footprint may still crowd smaller outlets or power strips, even with a compact design
- Cloud-dependent app control means functionality leans on SONOFF's servers and Wi-Fi stability
- No Amazon customer rating data is available yet for this specific listing, so you're relying on the brand's track record with earlier SONOFF plugs rather than crowd feedback on this exact version
At under $26 for four plugs, the SONOFF S40 is an easy recommendation for anyone dipping a toe into smart home gear. The energy monitoring is the real differentiator — it turns a basic on/off switch into something that can actually pay for itself by flagging the appliance that's costing more to run than you think. Skip it only if you need pure on/off scheduling and nothing more. For anyone who wants the data, this bundle is the low-risk way to get four plugs' worth of it at once.
If you're ready to see it for yourself, you can check current pricing and availability here: https://www.amazon.com/dp/B0C9ZV6TPH?tag=thebenchtest-20&tag=thebenchtest-20
