Need migration time estimate for 1T from 2011 iMac to M1 Mini via Thunderbolt

3.5 hours is my best guess. But my crystal ball is in the shop for its 30,000 year service and they're having a problem with calibration. It's a pre Christmas sort of thing when family asks me all sorts of questions about who wants/needs what for Christmas

If you want the fastest, easiest and most efficient method of migrating please use Setup Assistant and Migration Assistant. Do not use a wired connection between the 1 Macs or use WI-Fi, both are not a reliable and may extend the time to migrate. If you do not have a Time Machine backup of the 2011 iMac, create one!

I estimate your migration should be about 2-3 hours depending on the amount of data stored on the 2011. We get it has 1TB drive however I doubt it is filled to it's capacity otherwise it would not be working at all.

old_school_geek Said:

"Need migration time estimate for 1T from 2011 iMac to M1 Mini via Thunderbolt"

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It Will Vary:

The time depends of the amount of data and what is running in the back around. So, place these items atop a laptop cooler when performing this. The time remaining is only a guestimation on Apple's part, and as time progresses, the Estimated Time Remaining decreases --sometimes, impressively.

old_school_geek Said:

"Ummm, thanks. 1T means one terabyte (1000 gigabytes), and both computers will be running Migration Assistant but otherwise completely idle: screensavers & apps off. Can put the iMac in target disk mode if it’ll help, but I’m guessing the bottleneck[...]Have no laptop cooler, but it’ll be plenty cold there, even inside the house."

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Avoid Overheating:

Indeed, this is likely going to be slow, due to lots of data being transferred. But maybe getting a few laptop coolers would be ideal, rather than leaving them ration atop your desk..