So I know the basics - they’re strict on their bag sizes, they will fine you if it’s a mm over.
I have two bags which, according to the dimensions, fit the small bag size for Ryanair. I have purchased both a small bag and a large carry on bag.
Can I just measure them both in the small bag sizer? The worry with the big bag sizer is one is a backpack that slumps forward when placed on the ground, and the other is a hold-all style bag which would need to be placed on its side to fit the large bag sizer, and it will then fall out of the sizer.