Calculate square footage of house based on architectural floor plans

I have a two-story house and I would like to calculate the square footage of the living space.
I have the floor plans with measurements, and I have highlighted in red the outline of the living space on each floor. See attached.
For the main floor, I have attached the original architectural drawing so you can read the details/measurements, plus the same diagram with the living area outlined in red. For the basement I have included just the diagram with the outline in red with measurements taken by hand.
I would like somebody with experience to accurately calculate the size of the living area on each floor.
Along with the final calculations, I would like to see the method used to establish the figures. It will not be enough to say "the size is X".
Thank you for your interest in this project!