The standard size of a double DIN head unit is 180 x 100.3mm. Most vehicles have single DIN head units that feature the standard size. Double DIN has the same width as the single DIN system. The latter is taller than the single DIN unit. In fact, the length of the double DIN stereo system will be twice the length of the standard stereo. This feature allows you to turn your car into an entertainment space and stream any song you want on the stereo. Single DIN slots are 50mm. So, if you own a traditional model, chances are you will have the standard stereo slot.