Not what my training said. It's the flying "mass" of the unit, i.e. MTOM, Maximum Take-Off Mass. Or to be specific, that's the basic criteria but depending on Class, there can also be velocity (19m/s) and kinetic energy (80J) limits they, and especially the latter, relate to havier drones.
If I add even prop guards or a little plastic set of landing rails, by "under 250g" drone which is actually about 241g, goes over the 250g limit and nolonger qualifies for that class, so can't be used.
Note - it isn't the design mass, or mass at retail time, but a limit on the maximum mass as it takes off. The Mini 2 I have is pretty small, but I only have about 8g to play with before the MTOM would go over (or to be more accurate, not be less than) 250, which might include an ultr bright LED, or the prop gurds, skids I already mentioned. I can add any of those I like, but if it hits 250g or more as a result, it moves the drone out of subcategory A1 - Under 250g and into A1 Transitional. Until end of next year, these are treated as A1 aircraft, but in the >=250 and <500g section and even in transition, you mustn't fly over people intentionally, After transition ends, they will be treated as A3, unlike the sub-250g drones for which their current A1 provisions are permanent.
Anything of 500g or more, even during transition, is treated as A2 and mustn't be flown within 50m (horizontal distance) of (uninvolved) people. Over (or at) 500g and <2kg MTOM and they're classed as A3.
Argh. This is horrible to try to cover.
Let me try again.
After 1/1/23, all drones will either ber officially classified with a C rating (C0 to C4) depending on primarily, MTOM, but also maxspeed and kinetic energy.
They fall variously into the A1, A2 or A3 subcategory of the "Open" category.
All the old rules ceased to apply at the start of this year so, right now, unless a drone has a C lass (and unless it's lauched very recently, nothing does, anywhere), they'll be treated as "legacy" aircraft, and in various A1 to A3 subcategories until end of next year whentransition ends.
At that point, anything under 250g remains unaffected, but any legacy drones of 250g or more go into A3, which is substantially restricted.
Right now, weight classes go from sub 250g, 250-sub-500g, 500g to sub 2Kg and up. After transition, it changes a bit with another cutoff between 250 and 2kg at 900g, but we'll also by then either be flying drones with a C rating, or "legacy" but other than sub 250g, the "legacy" drones get treated much more harshly than in transition.
What you need in transition in terms of CAA approval also varies. Under 250g and you need an operator ID if it has a camera, and have read the drone manual. Over 250g and you need that, and a Flyer ID (which requires completing a basic online test called DMARES) and an A2 Cof C test.
This all changes around a bit after transition ends, but then it's down to sub-250g being effectively unchanged, "legacy" over 250g treated as A3, and everything else by the C0 to C4 class, which is restricted by MTOM, max speed and for some, kinetic energy.
In any event, since the start of this year at least, it's the MTOM that matters which, if a smartphone is on the drone, i.e. used as the camra system on the drone, will include the phone.
If, on the other hand, the phone is part of the controller unit and held by the operator, then it isn't part of MTOM because it stays firmly on the ground. But in that case, it's exactly how many existing drones (including my Mini 2) work right now .... unless you spend several hundred pounds on the uprated DJI controller which, last time I looked, didn't work with the Mini 2. So my phone is needed to operate my drone (clipped in and cabled up) but not in/on the drone.
You may well know all that, but I've tried (very badly) to cover it for anyone else that doesn't.
In relation to this thread, either the phone is flying with the drone, it wghich case it'' go way over the 250g MTOM and even in transition, you need an A2CofC, or it isn't in the drone in which case, it's the way most cheaper drones already work (except the toys, with just a cheap radio).
Phew. Sorry about the mess that post is but I can't be bothered to completely redo it.