Baggage sizer use at the gate? (No longer at gates after 23 Jan 2020)
 

When flying United, how often do the gate attendants make passengers place their carryons and personal items in the sizers to verify size? Thanks.

Rare unless it clearly oversized, and even that is not universal. Close cases will not be an issue.

I don't think I've ever seen it used. Only seen pax busted (including F pax) for carrying on more than two bags.

Rare.

My bag is pretty much right at the sizer's acceptable dimensions. I have had a couple of UA employees claim it was too big, but when I challenged them to check it in the sizer, they backed off without having me even put it in the sizer.

I have had non-UA staff insist I use the sizer (e.g. the AirServ guys while waiting in a TSA line!).

Funny, the only time I've ever been asked to use one was in Prague, in the LH sizer, not even UA.

Still, for the OP, if your bag is grossly over the allowed size, save yourself and your fellow passengers some trouble (or time) and just check it. If it's close, don't worry about it.

Bag sizer
 

My carryon is wheeless and soft sided and, in a test pack, can be squished to UA allowable size, 22 x 14 x 9. My personal item bag is also soft sided and, although it looks big, can be squished to 17 x 10 x 9. I'm not trying to game the system; I just don't want any surprises at the gate.
The only time I have ever witnessed a problem was at the gate of another major US airline. The flight was full and the gate attendants were looking for any reason at all to make passengers gate check their bags. They were borderline rude about it. I understand in a way after seeing people carry on huge suitcases clearly not meant to be overhead. I've seen people nearly break the overhead bins trying to force an oversized suitcase up there. I've also seen people put both their carryon and personal item overhead, not polite at all.
I wish I could pare down to what fits in an allowable personal underseat item.

The UA sizers are just slightly larger than the stated dimensions. If your bags meet the UA dimensions, don't worry about it. If you are asked, stick them in the sizer and off you go.

Remember, wheels & handles do count.

153 segments this year all domestic ,can recall 3x sizer was used

Careful with that statement. I always put my "Personal Item" in the overhead with my carry on, but these days I almost always have a pretty small carry on and usually can stack them on top of each other. Would you prefer that instead I take the maximum size carry on so I can put my laptop bag (personal item) inside of it, wasting a lot of space unnecessarily just so someone doesn't perceive me as being rude with 2 items up there?

The sizer is 10x15x23 giving an extra inch in each dimension. If it needs to be squished given the 11% extra leeway on the primary dimension (9) it's gonna be checked if it's my gate. How often do I use the sizer. maybe a half dozen to a dozen times per shift (LGA on a Friday evening/monday morning, maybe 5-10/flight.) After seeing upteen zillion bags over my career, I don't need the sizer, but if you don't believe my experience and you wish to challenge, the sizer is there for you. Anything that is being restrained by the sizer after squishing is significantly above the size allowed. A bag that snaps bag to oversized once it is removed from the constraints is oversized. The sizer isn't the rule, it's a template, the dimensions are the rule, which are smaller than the template, although a bag that fits in the template without being squished, even if slightly oversized will likely pass my muster. On the majority of aircraft, especially to business destinations, on narrowbody aircraft, many people that do conform need to check their bags due to finite space in the bins. If I have some that don't conform, those will go before those that do conform and only are at the end of line. Allowing oversized on while forcibly checking compliant bags in group 4/5 seems to me to be a poor application of published rues.

I got "caught" once leaving LAS because I had the expander unzipped. Nasty little lady forced me to to check it. I saw at least 20 people after me come thru with much bigger bags. It was a nice greeting for a F passenger..... but now I know to keep the expander zipped

That is often a good solution. Last month, I had a 90 min delay because on an inbound aircraft, an oversized bag was placed in the overhead bin, shifted, and made the bin unable to open. It shifted in flight and it took that long for the mechanics to come. I felt REALLY bad for the other guy whose bag was in the bin, as it was small, but could not be extricated. I've never sen a bin that couldn't be opened before due to oversized luggage, although I've seen many bins inopped, or small delays in getting them repaired. This was a first for me. The customers coming off the aircraft were all swearing about some passenger when I met the plane, had no clue what that was about until I realized it was the 1st class overhead bin that the bag owner and crew tried to open for about 5 min before allowing anyone to deplane as they were blocking the egress (single aisle aircraft, front row.)

Most suitcases are fine, the killers are some models wheels, and those expander pockets being packed to make the suitcases far bigger than 9' wide. I'd say 90% of the bags that are gate checked due to size are because the 9' are expanded into 11-15' by single and double expansion pockets.

My reality is that I rarely bring a bag like that, my carryon used always be my Think Tank roller camera bag that was designed to fit in the overhead and since it was filled with fragile, expensive gear I always made sure it was going to fit. Now that I am retired and just travel with a shoulder camera bag I made the mistake once and got caught. I was more annoyed by the attitude of the gate agent and the reality of seeing so many others carrying on so much other stuff.

Ironically, in the past three years where I have done one million miles, the only two times I saw agents make passengers use the sizer was at LAS.

I wonder how many of us simply haven't been around for anything past Group 1 to actually see it used?

I have never, ever seen it used but then again, I have also not been in anything but Group 1 or better in many years and I assume usage is a lot more frequent or enforced post G1 (not saying this as a "look at me DYKWIA" thing, but as a "maybe as FTers we suffer from situational/selection bias").