# Why Are Watts a Bad Measure for Kitchen Appliances? **URL:** \ **Category:** Factual Questions\ **Created:** [May 2, 2018, 4:19am UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452 "2018-05-02T04:19:23Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Tabby\_Cat](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tabby\_Cat](https://boards.straightdope.com/u/Tabby_Cat)\ **Post date:** [May 3, 2018, 7:51am UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452/21 "2018-05-03T07:51:16Z")
Yeah, heat is the one exception since in the end everything turns into heat. It’s impossible to make an inefficient heater. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [May 3, 2018, 10:07pm UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452/22 "2018-05-03T22:07:09Z")
> [@Tabby\_Cat](#): > > Yeah, heat is the one exception since in the end everything turns into heat. It’s impossible to make an inefficient heater. That’s a bit of an oversimplification, though, since you can and do lose efficiency when you consider where the heat is being applied. A poorly-insulated toaster, for example, is sending some of that wattage into your kitchen (or your kids’ hands) instead of to your toast. And there’s a difference in heating efficiency between, say, a toaster vs a toaster oven vs range oven vs microwave, even if all were 1000W. In 5 minutes, the microwave will cook more of your food than the range oven would. Some of the heat gets lost to ambient air, convection, radiation leaking out of the appliance, in the metal of the appliance itself, the magnetron, etc. Realistically, though, it matters a lot less for kitchen appliances (that you only use a few minutes a day) vs whole-house HVAC or the like. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [May 4, 2018, 1:06am UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452/23 "2018-05-04T01:06:31Z")
> [@Crafter\_Man](#): > > I am guessing the whole “RMS power” thing came about when someone said, “We measured the output voltage using an RMS voltmeter and the output current using an RMS ammeter. We then multiplied the two numbers and called it ‘RMS power.’” They had a thing they were telling consumers which was “peak power”. As in “500W” or (later) “500W music power” or “500Wpp”. “RMS power” is named in relation to that other kind of power figure. Note that in relation to “peak power”, “RMS power” /is/ average power. It’s the average root mean squared power, as against the peak power, which might not be the reactive peak power, but probably was – because who’s complaining? – actual power delivery depends on your speaker system anyway. A further issue is the Wikipedia continues to have no idea at all about the terms “average power” and “RMS power”, building on decades of published babel by people who had no idea at all what they were talking about, and thought that there was a distinction between RMS power and Average Power matching the distinction between RMS voltage and Average voltage Note that peak power (or music power) is actually an important number, particularly for audiophiles. So use of that number probably wasn’t originally dishonest. It’s just that when you are playing heavily distorted rock music, which is recorded with peak clipping anyway, the RMS power availability is what controls how load you can play it. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 4, 2018, 12:40pm UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452/24 "2018-05-04T12:40:40Z")
> [@Melbourne](#): > > A further issue is the Wikipedia continues to have no idea at all about the terms “average power” and “RMS power”, building on decades of published babel by people who had no idea at all what they were talking about, and thought that there was a distinction between RMS power and Average Power matching the distinction between RMS voltage and Average voltage. Agree, but it’s probably a lost cause. I doubt you’ll be able to convince a car stereo manufacturer or audio retailer that they should replace the term “RMS power” with “average power.” It’s too ingrained. Plus they probably have no idea what power _really_ is and how it’s measured. As mentioned by others, there’s a _ **lot** _ of woo, deception, and plain ol’ BS in the audio world. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [May 4, 2018, 1:11pm UTC](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452/25 "2018-05-04T13:11:44Z")
> [@Crafter\_Man](#): > > The Quora discussion is talking about RMS voltage and RMS current, both of which are valid concepts. They’re not talking about “RMS power.” > > It is perfectly valid to talk about average voltage, RMS voltage, and peak voltage. It is also perfectly valid to talk about average current, RMS current, and peak current. But when it comes to _power_, we are pretty much limited to discussing average power and peak power. RMS voltage and RMS current can be used to calculate average apparent power, and if you _also_ measure the phase angle you can calculate average real power. There’s no such thing as “RMS power.” As mentioned previously, when someone says “RMS power,” what they really mean is average power. this. it’s even more complicated with reactive loads like motors and loudspeakers, where the current waveform can both be out of phase with the voltage and be very oddly shaped. [Previous page](https://boards.straightdope.com/t/why-are-watts-a-bad-measure-for-kitchen-appliances/813452.md?page=1)