It varies pretty wildly, often efficiency ends up being dependent on the load since power supplies usually get optimized for a certain load range. Individually,

It varies pretty wildly, often efficiency ends up being dependent on the load since power supplies usually get optimized for a certain load range. Individually, the numbers might not look too bad, but when you think about how many individual AC->DC supplies you have, the losses can add up. I've been involved in a side project developing a consumer-friendly rating of "power quality" for AC devices and AC->DC power supplies which summarizes efficiency over a range of loads, as well as incorporating power factor measurements. We've been testing common devices such as USB power supplies for phones and such, as well as things like laptop power supplies, due to how numerous they are. We've had a few surprises, for example, Apple power supplies generally don't fare that well. Power Quality Score: https://pqs.app/ https://pqs.app/ Detailed test data is public for some devices but not all, since we're trying to find paths to revenue starting with subscriptions for full test results. Let us know if you have feedback. You might also be interested in the Youtube channel of my friend/PQS collaborator, where he's done some "deep dive" videos of testing some of the devices in the PQS database- particularly AC->DC USB power supplies due to how ubiquitous they are now- https://www.youtube.com/c/AllThingsOnePlace/ https://www.youtube.com/c/AllThingsOnePlace/ .