Occasionally I make toast, and it seems wasteful to heat the entire oven to toast a few pieces of bread. We’ve had people look at us funny when we use the full-size oven to make toast. Intuitively, one may think that a toaster or toaster oven would be more efficient to operate. On the other hand, counter space is sacred and I don’t want to waste it on a redundant appliance, so it warrants an in-depth investigation.
Search engines are becoming increasingly useless for these types of queries. So I figured I’d take a quick look at whether a toaster oven has a positive return on investment within a reasonable time span.
My oven uses natural gas and according to the manufacturer, the bake function uses 16,000 BTU per hour. A BTU is 1.0E-5 therms, so this converts to 0.16 therms per hour. If we assume it takes 5 minutes to toast bread (you really don’t have to wait for it to preheat), this becomes 0.0133 therms per toasting event.
In reality, the consumption is likely higher for short cooking times as the manufacturer only provides an average per hour, and the stove uses the most energy when first heating up, then much less to maintain the target temperature.
I was charged $2.17 per therm on my most recent natural gas bill. So it costs about 35 cents to run the stove for an hour, and 2.8 cents to make toast.
A mid-sized $90 toaster oven I looked up on Amazon, the Black and Decker TO3215SS model which handles 6 slices, uses 1500 Watts. If we assume the element is on the whole time it’s making toast this becomes an easy conversion of 1.5kWh to run the toaster oven. (Side note, a traditional standing 4 slice toaster looks to use around 1300 Watts, so a similar level of consumption.)
My electricity costs 32.9 cents per kWh. So running the toaster oven for an hour would cost 49.35 cents, assuming the heating element is on the whole time. Which it may very well be at higher temperatures as these toaster ovens are poorly insulated with only a glass pane for the door. To run for 5 minutes to make toast, this would be 4.11 cents.
Using averages over an hour, running the full-size gas oven is cheaper than running an electric toaster oven. Which is likely just a quirk of utility arbitrage; natural gas consistently tends to be cheaper than electricity per equivalent unit of energy.
However, we can do a thought exercise and say that even if the gas oven used 300% more fuel than the manufacturer’s stated average consumption while heating up, this would be 8.68 cents to make toast, saving about 4.5 cents per toasting event. You would need to make toast 2,000 times for the $90 toaster oven to pay for itself, which is about 5.5 years of daily morning toast. The toaster oven may break before then, as I’ve had a couple in the past that only lasted a few years each.
What about an electric oven for an apples to apples comparison?
The manufacturer of my oven offers a “dual fuel” version with an electrical oven component, a perfect comparison point. This uses 2850 Watts for the bake function, 1.9x more power than the toaster oven. Again, if we assume the elements are running at maximum power for the short 5 minute toasting event, we have 7.8 cents to use the full-size oven versus 4.11 cents for the toaster oven. Similar to the above example, we’re at over 2,400 toasting events to break even on the initial $90 cost of the toaster oven.
For longer baking events, it’s even possible for the full-size oven to be more economical than a toaster oven. It’s plausible that the better insulation it offers would result in the element running less than 50% of the time once it reaches operating temperature, whereas the toaster oven element may have to be running at full bore.
Conclusion: a toaster oven is a waste of money and counter space
Regardless of the fuel source of your full-size oven, it doesn’t seem realistic for a toaster oven to pay for itself with utility savings, as most owners seem to report them breaking in five years or less. Keep in mind that I live in Massachusetts with some of the highest utility prices in the US, comparable to across the pond in the UK. So for those who live where electricity is cheaper, it pushes the break-even point for the toaster oven out further and makes it even worse of a financial proposal.
It could certainly be reasonable and frugal for a single person or a couple to skip purchasing a full-size oven (thus pocketing the appliance cost) and do all of their cooking in one of the larger toaster ovens, but that’s a very niche use case.
As for myself I’ll continue toasting bread in my full-size natural gas oven now that logic has proven this to be a reasonable and possibly even the more frugal approach.