Sizing a wheelchair from height and weight

It appears I need to buy a wheelchair from local stock for somebody this morning, and I can’t measure her. But I know she is 5’2" tall and 216 lbs. Can I estimate from that? She has pretty wide hips and I’m guessing she would need at least a 20" seat, which seems to be the typical size for a “wide adult”. Can I tell in advance if that would be wide enough?

The folks at the wheelchair store should be able to advise you. IME that sort of equipment comes is two sizes: normal-to-wide and wide-to-yuge.

Unfortunately I think your user is right near the cut-off. Too big is a PITA, and too small is a different PITA. It also depends on how much time the user will spend in the chair. All day is different from a few minutes getting from here to there. the former might benefit more than the latter from a bit more width .

Seemingly. Later in the day I got a real wheelchair store that was open, and with this information they guessed she was on the border between an 18" and a 20", which I understand is the width of the seat at the hips. They wanted us to come into the store so they could do a good job sizing a chair to her, and she could see what felt best.
But the whole thing turned into a shitshow. She just had surgery and wanted to go home. She can walk and has never had a wheelchair, but she can’t walk well, and having surgery that day made it even harder (of course). She wanted to enter the house by crossing our 90’ long back yard, which is lumpy and mossy and had 3 days of rain on it. She wanted me to go indoors to bring her desk chair out, and wheel her across the lawn on these tiny casters. I said no way, but I’d do it in a real wheelchair if physical therapy cleared her for that. Thus the need to get it on a Saturday.
She would have none of this sizing nonsense, and said a wheelchair store would be too expensive anyway (I’m buying and it would have been fine). So, in a huff, she ordered something on Amazon for $100, that wasn’t going to be delivered for a couple days anyway, thereby solving all the wrong problems.
We used the garage entrance instead. And, now, she’s shuffling around indoors using a walker. I guess when the wheelchair arrives it’ll get shoved in the garage unopened, until the next time she needs help.
It’s been like this for 3 days now…

Ouch! When my late first wife was starting to get bad enough that it’d have been hard for her to get to the car in some future crisis that didn’t warrant an ambulance I went and bought a chair so it’d be ready if needed. In her case sizing wasn’t an issue. But for those of us of decent means, having something like that before you desperately need it is worth a lot. Because as you saw, there are few MacGyverable substitutes.

I’m sorry your first encounter became such a mess. But as you say, there will be another opportunity for this person to need a chair. And now she/you are ready.

FYI, lots of thrift stores have used DME like that for next to nothing. Aged Mom or Dad dies and the family just donates all that crap. At least around here in Retiree Central the thrift stores and senior centers are all but giving that stuff away; they have too much to store.