The boss of one of Australia's biggest banks has used International Women's Day to declare the company has closed the gender pay gap.

Westpac Banking Corporation chief executive Brian Hartzer told a parliamentary committee on Wednesday the bank has closed the gender pay gap at the bank on a "like-for-like basis".

Full-time female employees in the banking and insurance industry could expect to earn on average around $30,000 or 20 per cent less each year on base salary than men employed within the industry. Credit:AP

A like-for-like basis in the sense of the gender pay gap means paying both women and men the same amount to people doing the same job with the same experience.

But, other measures for pay equality in businesses include "organisational wide" and "by-level".