What Do The Numbers On Your Toaster Really Mean?

“So,” begins a popular if now ancient (at least, in internet years) meme. “Apparently the numbers on the toaster are minutes? I’ve thought for years it was degree of toasty-ness.”

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It’s immediately clear why the quip took off. It’s funny, sure – after all, what kind of measure is “toastiness” anyway? What scale would we even measure that on? – but it’s also kind of familiar. We hate to admit it so quickly after acknowledging the apparent absurdity of the whole “degrees of toastiness” concept, but whomst among us did not, deep down, assume the same thing? 

Of course, nobody likes feeling stupid – so, for those disinclined to admit to their own folly, the obvious rejoinder is this: that “minutes in toaster” and “degree of toastiness” are functionally the same thing. Leave your bread exposed to a heated nichrome wire for, say, six minutes, and it will, by simple laws of physics, become more toasted than if you take it out after two. You’re not foolish, you’re just using a derived measure rather than a direct one.

But it turns out, there’s an even simpler counterargument to the “timer over toastier” meme – and it’s that it’s just wrong.

“Toasters don't have timing chips on them. They're far too cheap for that,” pointed out veteran YouTuber Tom Scott in a 2014 video busting the meme. 

“What they have is a bi-metallic strip. Two bits of metal back-to-back, that heat up and expand at different rates, so the strip slowly curves,” he explained. “What you're changing with these dials is how far that strip has to curve before it triggers the thing that pops the toast up again.”

In more modern toasters, the setup is slightly different. That bi-metallic strip has been replaced with a capacitor, and the timer controls how fast it can collect current – a lower number on the dial equates to lower resistance through the circuit, and that means more charge being allowed into the capacitor at one time. 

“[The] capacitor accumulates the charge,” explained Daniil Nikitichev, then a research fellow in the department of Medical Physics at University College London, in 2021. “Once a specific voltage is reached, the circuit cuts off and toast is ready. Thus, by switching the dial we regulate the timer of the toaster.”

Now, you can argue that this is still a way of changing the amount of time your bread is toasted for, and you’d be right – but it’s very unlikely to be the literal minutes written on the dial. In Scott’s video, he tested four different toasters, setting all of them at “two” – all popped up at different times. And, in a similarly-inspired experiment at New Zealand outlet The Spinoff, physically timing each of the settings revealed zero adherence to the “one minute per setting” rule: setting one took 1 minute 30 to pop; setting two took 1 minute 49; three took 2 minutes 12; four took 2 minutes 38, all the way up to setting seven taking 3 minutes 55 to complete the toasting process. None of the steps between each interval were the same; they didn’t even uniformly increase or decrease. It was, in the investigator’s own words, “a fucking mess.”

So, what do the numbers on the toaster actually mean? Well, according to their own manufacturers, the dial controls the “browning” – or, to put it another way, the… well, the degree of toastiness.

We knew we should never have trusted a meme for engineering advice.