Here are some questions.
Do you need to minimize fabric purchase by piecing the border strips? It's a lot easier to calculate the yardage if you can simply purchase enough yardage to match the longest measurements.
Are the 16-inch, 6-inch, 4-inch and 6-inch specifications finished sizes? (I would assume so.)
Do you plan to miter the corners of the borders? (I would not.)
Do you plan on adding the border strip to the longest edges first? (This is what I would do.)