I ned help in measuring for a ceiling fan in the living room. The current fan has 5 blades
And I need to replace it... don't know what size I need.

I would get a 5 blader, unless it is a small room, and a Fan Control.
Many Areas, Blades should be no closer than 7'
From the ground.

If it's say 48", that's the most outside measurement of the blades. If the fan made a circle on the ceiling, it would be 48" in diameter. Get it? I hope so.

If you were happy with the performance of the old one then get another 5 blade 48". If you need more air moving increase that to 52" or higher. How high is your ceiling and is this flush mount or down rod install?

4 blades actually moves more air than 5 blades.

A 52" fan should be fine.

Frequently asked ceiling fan questions - Ceiling Fans N More