Assuming the oil level was good before doing an oil change, measure the amount of old oil that comes out and put the same amount of new oil back in - and the level will be good again. Here is an easy way to do it:
1) Drain the old oil into a basin, ideally a basin with a spout.
2) On the new oil bottles note where the level is, identifying it with a line drawn with a Sharpie marker.
3) Add the first quart (or liter) of new oil into the engine.
4) Using a funnel carefully fill the empty bottle of new oil with the used oil. Then pour the bottle of used oil into a jug or whatever you use to bring old oil somewhere for recycling.
5) Fill up the empty bottle again with used oil from the basin. It will show how much new oil from the next bottle is needed for the engine, and add that much new oil to the engine.
Of course all but the last empty bottle will get filled with used oil. But the last empty bottle will get partially filled - and this is the amount of new oil from the last new bottle that will need to get added to the engine, bringing it very close to the oil level that was there before starting the oil change.
Don't spill any of the used oil when pouring it from the basin into the empty bottle of new oil because it will mess up the measurements!
For whatever it is worth, I use this method when changing transmission fluid because for me it is harder to get the level of new transmission fluid right than it is to get the level of new engine oil, coolant/antifreeze, brake fluid, power steering fluid, etc., right.
