Super Saiyan 3 is the third stage of Super Saiyan. It is achieved by gaining even more massive power than a Super Saiyan 2. In the manga it is the pinnacle of saiyan transformations, this form however has many flaws like needing to gather lots of energy, cutting the time of the Fusion Dance, and drastically cutting Goku's time on earth while he was dead. Only 2 people in manga cannonicity have achieved this form, Goku and Gotenks. In the Raging Blast series of video games, Vegeta and Broly achieve this form. In the Japan-only arcade game Dragon Ball Heroes, Future Trunks can achieve this form.
This form has a power increase of 400X base power.