Best Smart Plugs With Energy Monitoring (Power Monitor Plugs)

The Short Answer

An energy-monitoring smart plug does two jobs: it shows how many watts whatever is plugged into it draws, including when it is “off”, and it lets you cut that power on a schedule. The first four picks below do both without a hub or a subscription; the fifth is a plain plug-in power meter with a screen and no app. Pick by the smart home system you already use:

Our pick for most homes: the Kasa KP125M, because Matter lets one plug join Alexa, Google, Apple Home or SmartThings, so it keeps working if you switch assistants later. The Wi-Fi plugs need a 2.4 GHz network. We chose them from manufacturer specifications; we do not test products in-house (how we choose).

Which Energy-Monitoring Plugs Work With Your Smart Home?

Control (on/off, schedules) and energy data are two different things. Most plugs pass on/off control to every assistant they support but show the watts only in their own app. Here is what each maker lists:

Home Assistant notes: its TP-Link integration connects to Kasa plugs locally but needs your TP-Link account for these models, and newer Kasa plugs do not report a running total, only live power (Home Assistant). The Shelly integration talks to the plug directly with no cloud connection (Home Assistant).

How Much Standby Power Is There to Find?

More than most people expect. The U.S. Department of Energy says the devices that draw power while switched off add up to almost 10% of residential electricity use. An NRDC study of 70,000 northern California homes measured an average always-on load of 164 watts, about 1,300 kWh a year and nearly 23% of those homes’ electricity (NRDC, 2015). Consumer electronics made up about half of it.

To price a single device, multiply its standby watts by 8.76 to get kilowatt-hours per year, then by the price per kWh on your bill. For example, a device idling at 20 W uses about 175 kWh a year, and a schedule that keeps it off 8 hours a night cuts that by a third.

1. Kasa EP25: Best for Apple HomeKit

TP-Link lists a 15 A / 1,800 W rating, real-time power readings with 7- and 30-day history in the Kasa app, schedules, timers and an Away mode, and HomeKit, Alexa and Google Assistant support. It is compact enough that two fit in one duplex outlet, and it is UL certified.

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Kasa EP25 Smart Plug with Energy Monitoring (4-pack)

HomeKit, Alexa and Google; real-time and 30-day energy history; 15 A.

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2. Kasa KP125M: Best for Matter

The Matter-certified version, so it works with Apple Home, Alexa, Google Home and SmartThings from one setup. TP-Link lists the same 15 A / 1,800 W resistive rating. One catch from the datasheet: energy monitoring is not available in the Apple Home app, so you still open the Kasa app to see the watts.

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Kasa KP125M Matter Smart Plug with Energy Monitoring (2-pack)

Matter-certified; energy data in the Kasa app; 15 A / 1,800 W.

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3. Emporia Smart Plug: Best With a Vue Panel Monitor

Emporia’s plug reports per-device energy use in the same app as the Emporia Vue panel monitor, so plug-level and circuit-level data sit side by side. It also works on its own, and Emporia says all app features, scheduling and cloud storage come with no subscription. Its continuous rating is lower than the Kasa plugs: 15 A peak but 10 A continuous, and Emporia warns that space heaters and portable air conditioners often exceed its limits.

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Emporia Energy Monitoring Smart Plug

Per-device energy tracking in the Emporia app; works with Alexa and Google; no subscription.

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4. Shelly Plug US Gen4: Best for Home Assistant

The most open plug here. Shelly lists a 15 A / 1,800 W resistive rating, a built-in voltmeter, ammeter and power and energy metering, and four radios: Wi-Fi, Bluetooth, Zigbee and Matter. It works with Alexa, Google Home, Apple Home and SmartThings (which also gets its power readings), and it can run schedules and automations locally, with MQTT and webhooks for tinkerers (Shelly).

Choose it if you run Home Assistant or want your energy data to stay on your network. Skip it if you just want the simplest app: the Kasa plugs are easier for most people.

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Shelly Plug US Gen4

Power and energy metering; Wi-Fi, Bluetooth, Zigbee and Matter; local Home Assistant control; 15 A / 1,800 W.

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5. Kill A Watt P4400: Best Plug-In Power Meter (No Wi-Fi)

Not a smart plug at all: you plug it in, plug the device into it, and read the screen. The datasheet lists 15 A / 1,875 VA, 0.2% accuracy, and readings for volts, amps, watts, hertz, VA, power factor and cumulative kilowatt-hours (P3 datasheet).

Choose it to measure one appliance after another, a fridge for a day, the TV stack for an evening, without any app, account or Wi-Fi. It cannot switch anything off, so pair it with a smart plug once you know where the waste is.

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Kill A Watt P4400

Plug-in meter: watts, kWh, volts, amps and power factor on an LCD; 15 A; no app needed.

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What to Plug In First

• The TV stack: TV, soundbar, streaming box, game console, cable box. Electronics were about half of the idle load NRDC measured.
• The home office: desktop tower, monitors, printer, speakers.
• Anything with a clock, glowing light or warm power brick that runs all day.

Do not use a smart plug for refrigerators and freezers, sump pumps, medical equipment, or space heaters (most heater manuals say to plug directly into a wall outlet, and heaters can exceed a plug’s continuous rating). Check the plug’s load rating against the device’s label either way.

A good routine: move one plug through three suspect areas over three nights, note the standby watts, then leave it on the worst offender. For a whole shelf of devices, a smart power strip is cheaper per outlet. For hardwired loads such as HVAC, the water heater or an EV charger, you need a panel energy monitor.

Frequently Asked Questions

Can a smart plug lower my electric bill?

Yes, on devices that draw power while idle. Multiply the standby watts the plug shows by 8.76 to get kWh per year, then by your rate, and schedule the plug off when you do not need the device. It saves nothing on devices that are already off at the wall.

What is the best smart plug with energy monitoring?

For most homes the Kasa KP125M, which works with Alexa, Google, Apple Home and SmartThings through Matter. Choose the Kasa EP25 for an Apple HomeKit home, the Emporia plug if you own an Emporia Vue, and the Shelly Plug US Gen4 for Home Assistant.

Which energy monitoring plugs work with Home Assistant?

The Shelly Plug US Gen4 works locally through Home Assistant’s Shelly integration with no cloud connection. Kasa EP25 and KP125M work through the TP-Link integration, which is also local but needs your TP-Link login for these models.

What is a power monitor plug?

A plug-in meter, such as the Kill A Watt P4400, that sits between the outlet and a device and shows how many watts and kilowatt-hours it uses. Unlike a smart plug, it has no app and cannot switch the device off.

Does the Kasa KP125M show energy use in Apple Home?

No. TP-Link notes that energy monitoring is not available in the Apple Home app; you view it in the Kasa app.

Can I put a space heater on a smart plug?

It is not recommended. Most heater manuals say to plug directly into a wall outlet, and Emporia says space heaters often exceed its plug’s 10 A continuous rating.

Do energy-monitoring smart plugs need a subscription?

None of our picks does. Emporia says all features and cloud storage are included, and the Kasa energy history is in the free Kasa app.

Related Guides

• Refoss vs Emporia Vue 3 — which panel monitor to buy
• Black Friday 2026 energy-saving deals — prices to beat on monitors, plugs and heaters
• What is vampire power? — where standby waste comes from
• Best smart power strip — for a whole shelf of devices
• Best home energy monitors — whole-home, circuit by circuit

Sources

• TP-Link: Kasa EP25P4 specifications
• TP-Link: KP125M datasheet (PDF)
• Emporia Help: Smart Plug compatibility and buying guide
• Emporia: Energy Monitoring Smart Plug
• Shelly: Plug US Gen4 documentation
• Home Assistant: Shelly integration
• Home Assistant: TP-Link Smart Home integration
• P3 International: Kill A Watt P4400 datasheet (PDF)
• NRDC: Home Idle Load (2015, PDF)
• U.S. DOE: Test your home energy IQ