How much is a shot of vodka equivalent to?

Had 16 shots of vodka last night.. luckily i ate bread and drank water/orange juice while drinking. I got home, drank some water and ended up throwing up the water. I felt terrible when i tried to sleep and only had 2 hours of sleep. Wake up, and given that detail, I kinda expected myself to be in awful condition. But to my surprise I'm not feeling that bad (i expected worse)