What is the ideal age for a girl to have sex?

"Many regret having sex too early or with someone they don't fully care about. I know of one girl who went through severe depression after losing her virginity".

That's because the girl is made to feel less virtuous. A fault of society largely. The association of value/emotions attached to the sexual act is a social construct and when a girl has her first sexual experience earlier than others, she is made to feel like a s***, that she is worthless and that she has no values.
This is the kind of guilt she is made to carry with her and it leads to mental health issues. Why do we as a society do this to our own. Accept sex as a normal event in a teen's life. We are a sophisticated society, yet we still impose such restrictions on girls. That is so shameful and totally unnecessary.

Girls should have sex whenever they want to have sex and with whomsoever they deem appropriate.

Teenagers may be physically ready for sex, but not emotionally ready. Most teen romances don't last long, and if sex is involved, the breakup is far more painful and difficult. Teenage girls and teenage boys look at sex differently, and most teenage boys are FAR too young to enter into a full intimate relationship with a girl, the way it should be done. Teenage girls don't realize this until the bad breakup happens. No, sex is NOT a normal event in a teen's life. Teenagers also never think that the girl can get pregnant- and then it happens, and then two scared teenagers have no idea what to do. I waited to have sex until I was 18 and in college, and engaged, and I have never been sorry for that choice.

Great reply but I choose to disagree. Not all teens attach emotions to sex. Early teens are more for the physical gratification. As they grow older they develop the need for emotional closeness and that need is fortified by the constant teachings of society and the mental priming that takes place in the girls life. Girls are constantly told that sex should be had in a setting of committment and emotional closeness and that the consequences of not doing that is hurt, heart break and pain. That is so wrong to be giving such advice.
I agree teen boys can be irresponsible and most teen pregnancies are in same age teen relationships. That's the reason I keep repeating that it is extremely important to make sure the girl is PREPARED and we should not be focussing on READINESS. Readiness is something that cant be achieved even when a girl is 30!! BUT, a girl can be prepared in case she succumbs to having sex because the environment was conducive to that act. Happens a lot at teen parties. If the girl is PREPARED then she can avoid pregnancy and that problem is solved. Why dont we teach girls to be PREPARED instead of focussing on readiness which is such a useless plan. It is crazy and very irresponsible not to teach a girl how to be prepared.
I agree teen boys are extremely immature. Hence, in my opinion, the girl is better off having a relationship with a much older mature, experienced guy who is benevolent, kind and patient with the girl. Those relations thrive BUT society and the law have outlawed such relationships.
I myself was in such a relationship when I was 13ish and the guy was much much older. He was my FIRST for everything. It was a full on sexual relationship, NOT because he took advantage of me. That's another shitty thing people tend to say when a much younger girl is in a sexual relationship with a much older guy. He was the best thing that happened to me and I never regretted that relationship that went on for 18 months. The relationship ceased because he had to go back to his own country. He was european and hence age difference wasnt an issue with both of us.
If you havent noticed, sex IS a normal part of a teens life. Ofcourse, like in your case there are exceptions and you delayed your first sexual excounter till you were 18. I had mine when I was 13ish and many of my friends have had experiences like mine at the same age as me and with much older guys who were in good jobs, had their own apartments and were great guys who took care of these girls. They are all so very happy, grounded, confident and doing exceptionally well in life.
So what you are trying to do is generalise and repeat exaxctly what society and parents do. Not a wise thing to do. Sorry.

The moment you have hit puberty. Thats how you are biologically wired. 

Thats called "experience" and you learn from experiences.
Just because the break up may sometimes be painful and difficult that is NO reason not to be in a relationship that may also involve sex.
Life is full of experiences and we become what we are through those experiences that make us aware, street wise, educated and smart. Those experiences give us the skills to be able to negotiate life and be successful later on.
Heartache, pain, disappointment and failures are all extremely important to develop, grow and gain those skills necessary to navigate through all the hardships in life.
So please, let teens experience life the way it was designed to be lived. Prepare them for those events, experiences and hardships. We have to get away from being shackled, stifled and Molly coddled.

what the HELL is wrong with you?

why the outburst? I dont see anything wrong with that reply. Each one to their own. As long as the girl has reached puberty, they are ready for sex and procreation. Nature's design is fabulous. Let's celebrate that instead of being negative and imposing morals and negativity.

you dont really need emotional readiness unless you want a long lasting relationship. A very young teen has sexual desires of the physical kind and will have crushes. Sex is not a bad thing while having a crush. All we need to make sure she is careful not to fall pregnant. As the teen grows older, towards the late teens, emotional needs take prioroty over physical need.
Thats the way it is. We need to understand this and accept this behaviour.

Great advice Alvin. Nothing but trouble awaits these young people. You don't need to do it just because every one else seems to be doing it.

I am ten and I have sex is that normal

It's a bit young

You know, you'll get in trouble if you do that, or worse, go to jail if you have sex with an underage girl. So I advise you, don't do that. Wait until you're at least mature enough and focus on your studies instead. In most countries, it is illegal to have sex with an underage person. So please please please, don't do that.

No, definitely not, you are too young for sex. I'd suggest you'd stop having sex and focus on your studies instead and wait until you're at least 21 to have sex after you finish school.

The age of consent in a majority of western countries is 16. However at this age many teen girls maybe ready physically ready for sex, but not emotionally. They are still kids. In my humble opinion 18 the ideal age for a young woman have intercourse. My daughter is 13. I told her she can date at 40

Probably a spare for the second round.