Plug-in power meter
P3 Kill A Watt P4400 Electricity Usage Monitor
The plug-through meter that sits between an outlet and any corded 120 V appliance and shows its real volts, amps, watts and cumulative kilowatt-hours.
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Best for
Measuring what one plug-in appliance really uses
Specifications
| Rating | 125 V AC max, 15 A max, 1,875 VA max |
|---|---|
| Displays | Volts, amps, watts, VA, Hz, power factor, kWh, elapsed time |
| kWh counter | 0.01–9,999 kWh (resets when unplugged) |
| Accuracy | 0.2% (manufacturer claim) |
| Size | 5⅛ × 2⅜ × 1⅝ in, 5 oz |
| Warranty | 6 months |
Specifications as published by P3 International. Confirm against the current spec sheet before buying — manufacturers revise models without renaming them.
What's good
- No tools, no panel, no app — plug it in, plug the appliance into it, read the screen
- True-RMS volts and amps, so motor and electronic loads read correctly, not just heaters
- Leave it for a day or a week and the kWh total is the number every cost estimate is guessing at
What's not
- 120 V corded loads up to 15 A only — it cannot measure a 240 V dryer, range, water heater or anything hardwired
- No cost display — multiply the kWh by your rate yourself (P3's P4460 EZ model does the math)
- The counters reset if it is unplugged or the power blinks
Our verdict
The fastest way to replace a nameplate guess with a measurement. Put it on the second fridge, the dehumidifier or the space heater for a full day, multiply the kilowatt-hours by your electricity rate, and you have what that appliance really costs. For anything hardwired or on a 240 V circuit, you need a panel monitor instead.
Compare with the alternatives
- Emporia Vue 3 Home Energy Monitor (16 circuit sensors) — measuring hardwired and 240 v loads, or every circuit at once