Most women believed they were being underpaid, sometimes by as much as 25%, and expected a bigger wage rise this year than men, according to research today.
A survey of more than 1,000 office workers showed that a third of women wanted a pay increase of up to 4% in 2011, slightly more than men's salary aspirations.
Almost one in three of the women questioned said they suspected colleagues at the same level were paid more, but most were unaware of industry rates for the job.
Men were more likely to know what they should be earning and were prepared to make sure their employer knew as well, said the report by a new salary comparative website, MySalaryChecker.com.
Andy Powell from recruitment firm Adecco, one of the firms behind the new site, said: "It's particularly disturbing that female workers have the perception that they are underpaid but are not confident in understanding what they may be worth in the jobs market.
"We would actively encourage both male and female workers to understand what the market rate is for their role, taking a realistic view of their skills and experience.
"Understanding what you are worth is one of the most important questions you can ask yourself when you are assessing a job offer, negotiating your salary, looking at qualifications or simply looking to make an impression in your role."