How to read stem measurements? I'm thinking of getting a shorter stem for my road bike. But I don't understand how they measure in terms of lenth and angle. 
I measured it from center to center and it came up to 4.25 inches. I'm guessing this is the standard 110 mm stem?
Length is measured center to center, and as you guessed, 110mm is roughly 4 1/4 inches. Angle is measured as difference from right angle, so a 0 degree stem will be actually pointing at 90 degree angle from the steerer tube. Yours looks something like 5 degrees.