Knowing when the turkey is “done” is the most anxiety-inducing part of cooking a turkey. You don’t want to food poison anyone, but you don’t want to serve dry, stringy meat (and shame) to you friends and family. A thermometer is imperative, but the little plastic “turkey timer” that comes stuck in your bird should be tossed directly into the trash.
If you’ve been cooking turkeys for a while, you probably already know this, but first-time bird roasters might be tempted to lean on the built-in temperature indicator. The problem is that it sucks. It’s garbage. It’s not your friend.
It is, however, a nifty little piece of technology; it’s just calibrated wrong. According to Cook’s Illustrated, it’s not that it doesn’t work, it just works at far too high of a temperature:
As we’ve covered previously, a turkey is a thermodynamic nightmare. It’s bulky and unwieldy, and the dark and light meat should (ideally) be cooked to two different temperatures. I cook the breast to 155℉ (it will rise another five degrees while resting) and the legs to 175-180℉ (or as hot as I can get them without the white meat over cooking). It does not, therefore, make sense to set a timer that pops up at 178℉ into the breast of the beast. Your turkey will be safe, but incredibly unpleasant to eat.
Instead, remove the blasted thing and get a digital instant read or probe thermometer. I have one with multiple probes so I can temp both regions of the bird at once (and it’s bluetooth enabled so I can check it right from my phone). This, coupled with spatchcocking or completely breaking down the bird before roasting, will ensure your turkey comes out safe and tasty.