Women who work in independent schools earn less than their state counterparts. Research shows their hourly pay was 7 per cent less for maths, science and engineering and 13 per cent less in other subjects.
Assuming they worked the same hours, this means a woman earning pound;30,000 a year in a state school would have earned just pound;27,900 in a private school if she was teaching a shortage subject, and pound;26,100 a year for other subjects.
In contrast, men who taught shortage subjects such as maths, science and engineering earned 22 per cent more in independent schools than their maintained school colleagues, the study for the Nuffield Foundation discovered.
The research compared male and female teachers with similar levels of experience in the two sectors.
Women teachers were paid less in private schools than in state schools across all subjects, including those that are difficult to recruit for.
Men, on the other hand, enjoyed a higher hourly rate for shortage subjects and the same hourly pay packet for other subjects.
Overall, men earned more than women in both sectors, but this could be because they held a greater number of senior positions.
Rosie Fielder, a housemistress at Wellington College in Berkshire, which has annual boarding fees of pound;25,620, took a 10 per cent pay cut when she joined the school as a chemistry teacher from state school Collingwood College in Surrey.
"I was head of sixth form and careers at my last school, so knew I would take a pay cut to become a regular teacher again," she said.
"But my husband was teaching here and there are other benefits. Some teachers get subsidised places for their children, which is a tax-free benefit, and as housemistress I do not have to pay rent or bills."
The study, The Economics of Private Schools, found that independent schoolteachers were generally better qualified than those in the state system. About 2,000 teachers a year were making the switch to private schools from the maintained sector.
The research - led by Professor Francis Green of Kent University and Professor Stephen Machin of University College London - found that, despite lower pay, female teachers' job satisfaction was enhanced by the smaller class sizes and more motivated pupils in private schools.
Overall, job satisfaction for men and women was higher in independent schools than state schools.
Mary Bousted, general secretary of the Association of Teachers and Lecturers, said the pay issue needed to be examined further. "It could be that women working in private schools are taking on more pastoral duties with longer hours. Schools need to be scrupulous in the fair treatment of men and women."
How the sexes compare
State Schools Independent Schools
Holidays (days per year) 59.2 65.8
Unpaid overtime (hours per week) 10.2 8.3
Usual hours per week 45.9 50.7
Gross weekly pay pound;634.70 pound;704.10
Holidays 57.3 58.6
Unpaid overtime 10.3 6.8
Usual hours 41.6 40.1
Gross weekly pay pound;517.90 pound;503.00
(Figures are taken from the Labour Force Survey, from 2001 to 2005. The gross weekly pay was calculated using January 2006 figures.)