How Is Delta V Loss Calculated for Spacecraft?

[Bluelogic32]

How do you calculate how much delta v is lost from gravity and atmospheric drag?
I've been looking for days but I can't find anything that actually tells me how it's calculated.
For example it takes 1.5 km/s - 2 km/s extra delta v for a low Earth orbit because of drag loss, how was that number calculated?

 

[Greg Bernhardt]

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?