Saving Pennies or Dollars? Unplugging the Microwave

saving pennies or dollarsSaving Pennies or Dollars is a new semi-regular series on The Simple Dollar, inspired by a great discussion on The Simple Dollar’s Facebook page concerning frugal tactics that might not really save that much money. I’m going to take some of the scenarios described by the readers there and try to break down the numbers to see if the savings is really worth the time invested.

Shelley said, “My husband insists on unplugging the microwave. Obviously this saves money but I feel like we are talking about pennies.”

When you’re discussing unplugging a device like a microwave (or a television or a VCR or other such items), you’re trying to avoid the device’s use of standby power. Standby power is a small but constant use of energy that does impact your electrical use for the month.

What’s standby power? Standby power is what powers the clock on your VCR or microwave or the “not currently in use” lights on your television or computer monitor. Those things stay on when you’re not using the device and thus require a tiny amount of power (compared to normal use of the item) all the time.

The Lawrence Berkeley National Laboratory has a very nice table showing the standby power usage of a lot of different types of devices. They vary widely.

Now, if you’ve looked up the usage of a device and want to know what it’s costing you, you’ll need the number from the first column in that table – the average consumption in watts.

In the case of a microwave in standby mode with the door closed, that’s 3.08 watts. 3.08 watts is the same as 0.00308 kilowatts.

Electric companies charge customers in the form of kilowatt-hours, which basically means if you use a device that consumes a kilowatt of energy for an hour, you’re charged whatever their kilowatt-hour energy rate is. The nationwide average hovers around $0.11 per kilowatt hour.

So, how much is Shelley’s microwave costing her per month to sit there plugged in in standby mode?

There are 24 hours in a day and 30 days in an average month, giving us 720 hours. Multiply that by the 0.00308 kilowatts her microwave is using and you get 2.22 kilowatt-hours per month. At a rate of $0.11 per kilowatt hour, the microwave is eating about $0.24 per month sitting there on standby mode.

This brings us bach to Shelley’s question about plugging and unplugging the microwave. In my opinion, if you’re a heavy microwave user, plugging and unplugging the device every day probably isn’t worth the quarter per month. In our home, the plugin for the microwave is actually behind a large shelf of cookbooks, meaning it would be a hassle to plug in and unplug the microwave. I certainly wouldn’t do that a few times a week to save a quarter per month.

If you rarely use the microwave – say, once a month or so – the quarter might very well be worth it. This is also true if the plugin area is really convenient for you or if it’s hooked to a switch so all you have to do is flick a convenient switch with your finger.

For me, though, the only time I might consider unplugging the microwave is if I were traveling for several days. In fact, I did unplug our microwave prior to our recent trip to Seattle, which saved us about ten cents or so.

Unplugging the microwave to save money on the standby energy use saves pennies, not dollars, and is probably not worth the additional effort unless the plug-in is very convenient.

Trent Hamm

Founder & Columnist

Trent Hamm founded The Simple Dollar in 2006 and still writes a daily column on personal finance. He’s the author of three books published by Simon & Schuster and Financial Times Press, has contributed to Business Insider, US News & World Report, Yahoo Finance, and Lifehacker, and his financial advice has been featured in The New York Times, TIME, Forbes, The Guardian, and elsewhere.