The Kilowatt Hour Explained

Like everyone else this winter, I’ve watched as my electrical bill has gone up and up and up. I’m not complaining, it’s cold and I’ve been using the heat to shield myself from the polar vortex lurking outside my walls.

But in looking at my bill, I realized that I really didn’t understand what I was looking at. Turns out, a good deal of people don’t exactly get it either. ‘Kilowatt Hour? What the heck is that?!’ Thankfully Google is here to answer all of my questions. Here’s what I learned:

Kilowatt Hour vs. Kilowatt

Your power company charges you based on Kilowatt Hours (kWh). That’s different from a Kilowatt (kW) in that Kilowatts are a measurement of power whereas Kilowatt Hours are a measurement of energy. Energy, for that matter, is a measurement of how much power is used over time. You can start to sense the relationship now – Kilowatt (power) and hour (time). Yes, every physicist teacher is groaning at this gross over-simplification of the universe, but you get the picture. A Kilowatt Hour is essentially (and for our purposes) a measurement of Kilowatts used over time.

Connecting Energy and Power

The equation used to calculate energy is Energy = Power * Time. So to find out how many Kilowatt Hours you use, you’d take kW * Time. As an example, if you use 903kWh per month (about average), that’s about 1.214kW over a period of 744 hours (for a 31 day month). To break it down even further, say you have a 1,000-watt heater (1kW) that you run for one hour. That equates to 1kWh (1kWh = 1kW * 1hour). It’s really pretty simple when you break it down.

This Stuff All Adds Up

So you’re using 1kWh for one hour of toasty 1,000-watt heater action. That doesn’t sound like a lot, but when you run a single heater for roughly 5 hours a day all month, that’s 155 hours of heater use. Using our equation, that’s also 155kWh of heater energy. If your power company is charging you peak prices during the winter, the price could be between 12-13 cents per kWh. So that’s an extra $20 a month for a single heater. It really starts to add up if you have, say 2 or 3 heaters, plus all those light bulbs, TVs, computers, etc.

And there you have it. Figuring out the price of heating your home through these cold winter months isn’t as complicated as one might imagine. As they say, knowledge is power, and knowing how much power you use as energy can help you see where your money is going. Might be time to unplug the heater and grab a blanket.