Calculating the proper square footage of work that you would be able to process through your EN bath is key for determining the proper costing for a job, as well as, providing a reference for proper bath performance. As we are trying to calculate for the square footage, or the area, that can be processed through a solution, you would also need to consider the thickness of your final product. As the thickness increases per part, the total amount of nickel eligible to be plated decreases, thus decreasing the amount of area that can be plated.
https://www.pfonline.com/articles/calculating-electroless-nickel-square-footage