Not sure what you mean. You need to think both inches and yards. 1 moa is (roughly) one inch at 100 yards, 2 inches at 200 yards ECT. That's why if you think in yards and inches, using the MIL system you have to do the conversion from cm/m.
Just like Kthomas says. If you miss by .2Mil you miss by .2Mil and make an adjustment. I guess if you missed by .5MOA you could just adjust .5MOA as well.
With a matching reticle/turret combo no conversions are required. Using a Mil-Dot Reticle with MOA turrets does require work. If you are off by 1 MIL on target you would need to adjust for 3 MOA (approximately) on the turrets. Some people may say that they missed by 3 inches and then convert that to MOA or MIL and then adjust but if you just use your reticle it is easier.