Vehicle voltage will swing normally from the 11's to the 14's based on whats happening. A running vehicle with a properly performing charging system will run low 14's with a low load especially at RPM's above idle. Turn all the junk on (HVAC, wipers, Headlights, radios, heated everything, etc.) and you will likely idle in the mid 13's.
Idle around town with all of this stuff on, roll into your driveway, shut it off, leave it overnight and restart it in the morning on a cold night with the heater running immediately on restart and seeing low 11's or less while cranking is not out of the question.
Having said all of that, if you are concerned that your vehicle seems to run low voltages more than it usually does, take it to a trusted shop for an AVR test. They will check your electrical system and let you know of any issues with battery, starter, alternator and all connections.