This isn't really meant to be a stellar art piece so much as it is a resource for creating other art pieces. I created this nifty height chart for the purpose of helping others with their own fanart.

This chart is pretty accurate, due to having created an accurate scaled-down ruler to put the characters on top of. The ruler is what you see in the background there. Each small red and blue square is an inch, and each long light gray and medium gray rectangle is a foot. Japanese source books state that Mega Man is 132cm tall and X is 160cm tall, so by converting that into feet and inches as best as I can, it means that Mega Man is 4'4" and X is 5'3". This is pretty accurately reflected on this chart.

Although I don't have the official measurements for anyone other than X and Mega Man (which were taken from the official "Rockman & Rockman X Daizukan" source book), I can assure you that the conjecture in this chart is pretty accurate as I've examined all the characters used here and compared many pictures in which they've appeared together (along with extensive studying of model sheets from the "Mega Man Official Complete Works" and "Mega Man X Official Complete Works" art books) to get the most accurate height chart possible.

The purpose of this height chart is for anyone who wants to make art of these characters and have their sizes be accurate. I dunno if I'm all that good at always keeping height consistency between characters in my art, I'll admit (I'm working on improving that), but hopefully this height chart may prove useful for me in the future, and to anyone else that does Mega Man fanart.

EDIT: Since people seem to keep asking what the heights are, I'll go ahead and list them down. As I said before, though, keep in mind that the measurements are only approximate with about a one inch margin of error, and that the chart was made by viewing heights compared between characters through various sources (sometimes made a little difficult when different official sources contradict each other, but I took that into account as much as I could and went with whatever official sources outnumbered the contradictions).

Mega Man - 4'4" (Official)
Dr. Light - 4'9"
Proto Man - 4'4"
Roll - 4'4"
Kalinka (child) - 4'4"
Bass - 4'4" (I'll admit I'm not completely sure about this one as there seems to be about as much official art that has him about two inches taller than Mega Man as there is official art that has him the same height)
Dr. Wily - 4'9"
X - 5'3" (Official)
Alia - 5'3"
Zero - 5'6"
Iris - 5'
Sigma - 7'5"
Volnutt - 5'1"
Roll Caskett - 5'1"
Tron Bonne - 5'1"