While gliders have made significant advances over the last 50 years, airliners seem stuck with an 18 to 1 glide ratio. But this makes the math easy.
If you are 4500 AGL you should have 13.5 track miles to the airport. Plus some to slow and configure and +/- some for the wind. It's all well and good to figure all this out but ATC will most times vector you around and screw up whatever plans you or the box had.