Gareth Brown, 28, was handed the lengthy sentence after a judge told him her poses a serious of causing physical and psychological harm to women.
Leeds Crown Court heard Brown attacked his first victim at a house in Leeds on March 25 this year as she was asleep in bed.
Brown used his hand to cover the young woman’s mouth and nose until she passed out.
She awoke to find her underwear had been removed and Brown carrying out a sex assault upon her.
The incident was reported to the police but Brown denied the offence and was granted bail as he had no previous convictions.
DNA was later found which linked him to the offence.
The second offence took place 58 days later at another property in Leeds.
Brown forced open a bathroom door as the victim was using the toilet.
He then forced her into the bath and said to her: “You want this, I know you do.”
Brown again used his hand to cover the woman’s nose and mouth to stop her breathing.
Describing the incident, she told police officers: “I thought I was going to die. I couldn’t fight him because he was so strong.”
The victim’s friend came to her rescue as she heard her screams.
Brown, of Wickham Street, Beeston, Leeds, pleaded guilty to a sexual assault and assault occasioning actual bodily harm with intent to commit a sexual offence.
Caroline Wiggin, mitigating, said Brown was ashamed of what he had done and was willing to accept help to address his offending while in custody.
She said: “He has lost his girlfriend, his accommodation and his job as a result of what he did.”
Sentencing Brown, Recorder Richard Woolfall said: “It must have been a terrible ordeal for both of these ladies as they were struggling for breath”
“I have no hesitation in finding that you are dangerous.
“I find there is a significant risk that you will commit further offences in the future. You use violence to subdue your victims and in doing so you will cause psychological and physical harm.”
Brown was told he must serve at least two thirds of a six and half year custodial period followed by an extended period of five years on licence.