Does anyone know where sg sources the seat width? Is it from the horse's mouth?
From the SeatGuru website:
"At SeatGuru, we love travel, but we can't fly on every single plane. So we turn to you, our community, for the real truth on seat width, pitch, and comfort."
Should tell you all you need to know.
For the record, 777 economy seat width is typically around 18" in 9-abreast and 17" in 10-abreast, though I can't comment specifically on KLM.