Price unavailable right now
Updated November 2026
Data from the official Sonoff and TP-Link sites.
2026 verdict
For most buyers in 2026, TP-Link Kasa EP40 is the safer pick over Sonoff S31 WiFi Smart Plug because of rating, weather resistance, and maximum load power.
It has the clearer edge on rating, weather resistance, and maximum load power, and it stays ahead on its broader overall balance. There is still a case for Sonoff S31 WiFi Smart Plug, but mainly if energy monitoring and integrations are what you value most. That makes TP-Link Kasa EP40 the clearer recommendation in 2026.
Connectivity
- Wi-Fi 2.4 GHz
vs
Winner
24% OFF
$18.99
$24.99
Connectivity
- Wi-Fi 2.4 GHz
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| Feature | Sonoff S31 WiFi Smart Plug | TP-Link Kasa EP40 | Winner |
|---|---|---|---|
| Rating | 4.1 | 4.6 | TP-Link Kasa EP40 |
| Weather Resistance | NO | IP64 | TP-Link Kasa EP40 |
| Maximum Load Power | 1800W | 1875W | TP-Link Kasa EP40 |
| Energy Monitoring | YES | NO | Sonoff S31 WiFi Smart Plug |
| Integrations | Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter | Google Home, Alexa, Samsung SmartThings, Home Assistant | Sonoff S31 WiFi Smart Plug |
| Plug Format | Type B | Type B | Tie |
| Connectivity | 2.4 GHz WiFi | 2.4 GHz WiFi | Tie |
| On/Off Button | YES | YES | Tie |
| Zigbee Router | NO | NO | Tie |
| Local Control | YES | YES | Tie |
Price unavailable right now
- + Energy Monitoring: YES
- + Integrations: Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
- - Rating: 4.1 vs 4.6
- - Weather Resistance: NO vs IP64
Winner
24% OFF
$18.99
$24.99
- + Rating: 4.6
- + Weather Resistance: IP64
- + Maximum Load Power: 1875W
- - Energy Monitoring: NO vs YES
- - Integrations: Google Home, Alexa, Samsung SmartThings, Home Assistant vs Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
Frequently Asked Questions
Which is better overall: Sonoff S31 WiFi Smart Plug or TP-Link Kasa EP40?
TP-Link Kasa EP40 has the stronger overall profile in this comparison, especially for rating, weather resistance, and maximum load power.
What is the biggest difference between Sonoff S31 WiFi Smart Plug and TP-Link Kasa EP40?
Rating is one of the clearest differences: Sonoff S31 WiFi Smart Plug lists 4.1, while TP-Link Kasa EP40 lists 4.6.
Who should buy Sonoff S31 WiFi Smart Plug?
Choose Sonoff S31 WiFi Smart Plug if your priority is energy monitoring and integrations and that matters more than rating.
Who should buy TP-Link Kasa EP40?
Choose TP-Link Kasa EP40 if your priority is rating and weather resistance and that matters more than energy monitoring.
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