Best Energy Monitors & Smart Plugs
A plain comparison of plug-in smart plugs and whole-home energy monitors, with real examples of each, so you can see what's driving your bill.
If you want to know what's actually driving your electric bill instead of guessing, an energy monitor measures it directly instead of relying on typical-usage estimates.
Two different jobs
Energy monitors split into two categories that answer different questions. A plug-level monitor plugs in between a single device and the wall outlet and shows exactly what that one item draws, in real time and often over a longer log. A whole-home monitor installs at your breaker panel and tracks your entire home's usage, either broken down by individual circuit or estimated appliance-by-appliance using each device's electrical signature.
Plug-level monitors
These are the simplest and cheapest way to answer "what does this one thing actually cost to run?" A standalone unit like the Kill A Watt (currently the P4460 model) plugs directly into the wall with the device plugged into it, showing live wattage and cumulative kWh on its own screen, no app or account required. A monitoring smart plug does something similar but reports to a phone app and can often add scheduling or remote shutoff on top of the monitoring, at the cost of needing Wi-Fi and an account. Both are the right tool when you have one or two specific appliances you're curious about, since the appliance guides on this site already give you typical wattage ranges, while a plug-level monitor tells you your specific unit's real number instead of a typical range.
Whole-home monitors
A whole-home monitor installs inside or near your electrical panel (often by an electrician, since it involves working inside live panel wiring) and measures your entire home's draw directly. Some, like the Emporia Vue, use physical current clamps on individual circuits, giving you a true per-circuit breakdown. Others, like the Sense Energy Monitor, measure total home draw and use software to automatically recognize individual appliances by their electrical "signature," which is convenient but less precise at attributing usage to a specific device than a true per-circuit or plug-level reading.
What to look for before you buy
No product on this page was tested by us, so instead of a ranked list, here are the differences that actually decide which device fits:
- Voltage. Most plug-level monitors are built for standard 120 V outlets, so they can't measure a 240 V dryer, range, or water heater. A whole-home monitor at the panel can.
- How it tells appliances apart. Per-circuit current clamps, like the Emporia Vue's, read each circuit directly. Signature detection, like Sense's, estimates individual devices from your total usage, which is convenient but less precise.
- Where you read the data. A standalone meter like the Kill A Watt shows readings on its own screen with no app or account. Smart plugs and whole-home monitors report to a phone app and need Wi-Fi.
- Installation. Plug-level devices just plug in. Whole-home monitors go inside the electrical panel, usually installed by an electrician.
- Whether it can act on what it measures. Some smart plugs add schedules or remote shutoff on top of monitoring, which is where the savings actually come from.
Which one makes sense for you
Start with a plug-level monitor if your question is about one or two specific appliances, since it's cheaper, needs no installation, and gives you a direct, precise number for exactly what you plugged in. Consider a whole-home monitor if you want an ongoing, complete view of your entire home's usage, including hardwired equipment like a water heater or HVAC system that a plug-level monitor simply can't reach, and you're comfortable with (or plan to hire an electrician for) the panel-level installation. To see what a monitor is likely to find, read how much standby power a typical home uses.
The specific products named on this page are drawn from an independent product roundup (Your Best Digs' electricity usage monitor reviews), rather than tested by us directly. We're not currently affiliated with any of these products and don't receive compensation for mentioning them; if that changes, this page will say so plainly. Last checked September 2026. Cedrick Reese wrote this guide and rechecks the product details against the roundup above.
Frequently asked questions
What's the difference between a plug-level monitor and a whole-home monitor?
A plug-level monitor (like a Kill A Watt or a monitoring smart plug) sits between one device and the outlet, showing exactly what that single item draws. A whole-home monitor installs at your electrical panel and tracks your entire home's usage, often breaking it down by circuit or by automatically identifying individual appliances' signatures.
Do I need a whole-home monitor, or is a plug-level one enough?
If you're curious about one or two specific appliances (a space heater, an old refrigerator, a window AC), a plug-level monitor answers that directly and costs much less. A whole-home monitor makes more sense if you want an ongoing, complete picture of your usage across everything, including hardwired appliances like a water heater or HVAC system that a plug-level monitor can't reach.
Does a smart plug save electricity by itself?
Not automatically, though it can enable savings: a monitoring smart plug shows you what a device actually draws (including standby/phantom power when it's "off"), and a scheduling smart plug can cut power to something you'd otherwise leave running, like a space heater or a charger. The savings come from what you do with the information, not from the plug itself.
How accurate are these devices?
Plug-level monitors are generally quite accurate for the single device plugged into them, since they measure it directly. Whole-home monitors that automatically detect individual appliances by their electrical signature are less precise at attributing usage to a specific device, though their total-home number is generally reliable since it's measured directly at the panel.
Related tools
- Appliance Database: typical wattage ranges if you don't have a monitor yet
- Electricity Usage & Cost Calculator
This page provides general product category information, not personalized purchase advice or professional installation guidance. Always follow manufacturer instructions and local electrical code, and use a licensed electrician for any panel-level installation.