What it is
The Kill A Watt is a plug-in electricity usage monitor. Plug it into any outlet, plug your device into it, and it displays real-time wattage, voltage, amperage, frequency, and kilowatt-hours consumed over time. No setup, no WiFi, no app required. It costs under $30 and has been a standard home energy audit tool since its introduction by P3 International.
Why we picked this
The Kill A Watt is the simplest way to answer the question 'how much electricity does this thing actually use?' Plug in your old fridge for 24 hours and you know exactly what it costs you per month. Plug in your gaming PC and see the difference between gaming and sleep mode. The Kill A Watt consistently reveals that the devices people worry about (phone chargers, LED bulbs) use almost nothing, while the devices they ignore (old fridges, space heaters, dehumidifiers) are the real culprits.
Key takeaways
- At under $30, the Kill A Watt pays for itself by identifying one inefficient device. Replacing a 15-year-old fridge (often 150+ kWh/month) with an Energy Star model saves $100+ annually.
- Standby power ('vampire draw') from entertainment systems, chargers, and smart home devices typically adds 5 to 10% to residential electricity bills.
- The device requires zero technical knowledge: plug in, read the display. No WiFi, no account creation, no app downloads.