WOMEN managers could be $13,500 a year better off a year on average if only they had a sex change. That is the penalty managers pay simply for being female, new research shows.

The research reveals that most workplaces today bear little resemblance to the misogynist office of the 1960s depicted in the hit TV series Mad Men. Yet women full-time managers on average earn 25 per cent, or $22,000, less than their male counterparts. And while some of that difference can be explained by factors such as women working fewer hours than men, most is likely to be due to discrimination, says Dr Ian Watson of Macquarie University.

"The idea that management is a male preserve as depicted in Mad Men is so outdated," he said. "Since the 1970s women have been coming through universities and into management."

Despite the progress, men are twice as likely to become managers as women, and if women have young children, their odds shrink further.

But remarkably, the women who do make it into management ranks are similar to men in most ways that count. The factors once thought crucial in explaining the gender wage gap at management level are hardly relevant today.