I’ve never done it with a turkey. Maybe these might help if you scroll to the cooking instructions.

Serious Eats - Spatchcock Turkey

Milk Street - Spatchcock Turkey

Do you have an instant read thermometer? I think that's the best way to determine cooking time, since ovens can be variable. It also depends on the size of the bird, of course.

The size of the turkey will make a huge difference. It will certainly take a shorter time than a regular turkey prep.

I see the National Turkey Federation suggests about 6 minutes a pound at 400-425. As Carol mentioned, rely on a thermometer to check for doneness. Start checking early after it’s been in the oven at 4 minutes a pound.

We do our turkey's on a charcoal grill and it's all of an hour and a half but there are too many variables for this to be helpful to you.

Prior suggestions to let a thermometer be your ultimate guide are right on. Recipes and directions are only general recommendations, there are too many variables that affect the ultimate outcome.

One major variable not always considered---- what was the temperature of the raw meat when it first started cooking? Some fridges can be much colder than others, or it may have sat out in the air for a longer or shorter time. Both can affect cooking time.

I always start checking when it reaches about the 80% of recommended time point. If you discover it took less time than expected after it's already been cooking for too long, it's too late to fix it.

"I always start checking when it reaches about the 80% of recommended time point."

It's the recommended time point I'm looking for here. Some sort of ballpark based on bird size or per pound.

That wasn't the question you asked. You said

" How long do you roast a spatchcocked turkey? "

The answer to this question is - you roast it until it reaches the recommended temperature, which will be more or less than the recommended time in the recipe you choose to follow.

I wasn't the only one who suggested that you need to pay more attention to temperature than time. Cholebud also suggested as I did that should start checking early on.

My last large turkey was in pieces rather than spatchcocked, but all touching. It cooked surprisingly fast, so I agree with the prior recommendations: Check the temperature early, and check different parts. I've seen the same timing as Chloebud from different sources. Mostly 6 min./lb., and one which said 6-8.

Knowing approximately how long to cook something is important for planning and timing purposes.

"That wasn't the question you asked. You said " How long do you roast a spatchcocked turkey? "

That was only PART of what I asked. Here is the excerpt from my original post: "My question is: How long do you roast a spatchcocked turkey? Obviously the size is variable -- approximately how many minutes per pound? Or approximate time per size range? I don't want to assume it's the same as chicken (5# range took about 45 minutes @ 425F)."

I reiterate: Knowing approximately how long to cook something is important for planning and timing purposes.

An above source was cited as cooking 6 minutes per pound @ 400-425, check at 4 minutes per pound. That doesn't seem to align with my experience with the chickens, that is around 9 minutes per pound. One of the links indicates the same -- somewhere around 9 minutes/pound. I forgot about Butterball website; there I found around 10-12 minutes/pound at a lower temp of 375.

Leave it to Martha 😄

I find it INSANE when people suggest the obvious🤦. Is there a person cooking a large (ANY) piece of meat that doesn't let a thermometer be their guide?!?!?!?! Spatchcocked is the hour and a half, a whole has taken us up to three hours. Charcoal/outside temp (Thanksgiving in MN is where this happens), size of bird. Our turkeys once spatchcocked fill the grill of a Webber kettle, as close to 25lbs as I can get.

Yeah. There are a lot of people who don't have a meat thermometer at all.

If the legs move easily, the bird is done. I use a thermometer now, but cooked for 30 years before one existed. You grab the end of the leg and pull. If done it moves and pulls loose easily.

Chicken, turkey, steaks, whatever, no thermometer. You just knew when it was done.

" There are a lot of people who don't have a meat thermometer at all. "

I try to share meals with people like that either at my house or in a restaurant. Life is too short to eat bad food or drink bad wine.

I have consulted this YouTube video the three times I roasted a spatchcock turkey. https://www.youtube.com/watch?v=oDSkekArb There's a step where he pours boiling water over the bird before roasting. The results have been fabulous.