Grave sin (as are sodomy, fornication, and adultery) particularly when accompanied by pornography. Why do you ask? Are you trying to make excuses for something?
The "anti-judgmental" attitude you seem to be displaying, and which has been widely adopted in our corrupt culture, is most of the reason we have "drag-queen story hour".
BTW, contraception and abortion are also grave sins ... just in case you were going there next.
Repent, while you still can.