A new study has found that female engineers earn significantly less than men, with the disparity in salaries hitting its peak at the key mid-career stage.

The 2013 global salary report of professionals in the engineering and optics sector released by the International Society for Optics and Photonics (SPIE) found that the median salary for male engineers was 36 per cent higher than that for women overall, at $79,755 and $58,431, respectively.

The income gap between male and female engineers hits its peak during the mid-career phase. After spending 16  to 20 years in the work force men earned 43 per cent more than women, compared to eight per cent after only several years of employment.

This disparity tapers down modestly as career length increases, however, with men earning around 24 per cent more than women are three decades in the workforce.

Pay differences also varied depending on the type of employers. At “other research institutes” men earned 79 per cent than women, while in civilian government jobs, the disparity is only 11 per cent.

In addition to earning higher salaries male engineers also work much longer hours than their female counterparts. Between 25 and 30 per cent of the male survey respondents said they work 50 or more hours per week, as compared to only 20 per cent of female respondents. While this increased work load may contribute to the disparity in earning levels by gender, the authors of the study say it is likely just one of many factors.

The size of salary differences also varies considerably by geographic region. The Middle East leads the pack in terms of gender-based income disparities, with men in the region earning 140 per cent more than women employed in technical fields at all income levels. In Asia, men earn 63 per cent more than women in higher income technical occupations, while in Europe this figure is 41 per cent.

In North America, male technical professionals at all income levels make 32 per cent more than women, while Oceania is home to the smallest gender-based earnings gap in technical fields, with men making only nine per cent more than women.

The survey, conducted by SPIE in April, received a total of 6,752 valid responses, of which 83 per cent were provided by men.