However, if I was dating a woman, and attempting to build a relationship with her, I would expect her to be honest about significant details of her past.If I later learned that she'd covered up a very significant detail of her past, I'd likely never trust her completely again...without that trust, a healthy relationship can't exist.
Depending on how long ago it was, a lot of people will overlook stupid stuff you did when you were 19.. You CANNOT tell by looking at me or even talking to me...thanx If it is serious crime, you must tell her. Trust is very important and I would worry of what other thing you hide.
If it was more recent, it might be harder to convince a potential mate that you've turned your life around. Perhap not on first date, not you can not allow a relationship to develope without this be told. To me it comes down to respect - both for myself (I need someone to love and accept ALL of me - demons included) and for others ( people should be free to decide which demons they can deal with).
To most people who you meet, or who glance at your profile, or who messages you once or twice, it's none of their damned business.
But if it's someone who you're actually interested in pursuing a relationship with, you should tell them. I think you should be open and honest about your past no matter what the situation.
I don't think you should put it in your profile though.