Monitoring outdoor power prices

Through our thorough testing, we've identified the best Power Cost Electricity Meters for accuracy, ease of use, and comprehensive features. Here are NerdTechy's top picks: P3 International 'Kill a Watt' – The original, and arguably still the best, power usage monitor on the market.

P3 International 'Kill a Watt' – The original, and arguably still the best, power usage monitor on the market. It's exceptionally accurate, and provides a variety of measurements. That said, it doesn't actually tell you the cost of your power. So if your concerns are economical rather than practical or environmental, you'll still have math to do.

As for accuracy, you're looking at one of the best-performing electricity usage monitors on the market. It's accurate to 0.2 percent, which is truly exceptional. A measurement of 120 volts, for example, would be accurate to within 0.24 volts. A measurement of five watts would be accurate to 0.01 watts.

Power Cost Electricity Meters are here to answer that. These devices measure the energy consumption of your electrical appliances, translating it into actual costs. This helps you understand which devices are energy hogs and where you can save on your electricity bill.

Power usage is measured in kWh every 24 hours. When a full day has passed after plugging in your device, the total power usage for that day will be displayed. At that point, you'll have two options. You can either view the last day's average, or the current day's average.

Beneath the LCD display and above the power outlet, you'll see a row of five buttons. They're mid-sized and rubbery, ideal for easy operation without removing the meter from your outlet. The first three switch measurement units between volts, amps, and watts or volt-amps respectively. The fourth can be used to measure Hz or power frequency.