Women in the UK typically save less than one-third of what their male counterparts do for retirement, research by the Pensions Policy Institute (PPI) has uncovered.
The findings show that the average pension pot for women in their 60s is around £51,100, compared to £156,500 for men, with part-time working largely to blame.
Working part-time is thought to be responsible for a 47% cut in women's pension wealth by their late 50s, compared with a 28% reduction caused by the gender pay gap.
This is compounded by the fact that women live 3.7 more years than men on average, meaning that their pensions need to last longer.
The researchers found that women need to save approximately 5-7% more than men on average if they are to drawn the same pension income throughout their retired life.
Joanne Segars, chair of trustees at NOW: Pensions, which commissioned the research, said that the "part-time pensions penalty" must not be ignored any longer.
"Policy and regulation around saving for retirement need to change to better reflect the changes in the workplace and society," she continued.
"Small changes to auto-enrolment could make a big difference for women, but to really bridge the gap, more needs to be done to help mums remain in the workforce."
The analysis shows that a record 71.4% of women are now in work, but that 41% of these were working part-time in the last quarter of 2018, compared with 13% of men.
And a part-time salary might mean that they do not meet the £10,000 a year threshold needed in a single job to be automatically enrolled into a workplace pension scheme.
NOW: Pensions called for an end to the £10,000 auto-enrolment trigger, and said that workplace pension contributions should be paid on every pound of earnings.
This could bring 1.4 million women into pension saving and boost wealth by 140%, while improving the availability of childcare and reforming divorce settlements are also suggested.
And a 'family carer's top up' could help too, with the government paying the equivalent of an employer's contribution at national living wage level when women take time out of work to care.
"The shocking pensions gap that women experience is a result of a lifetime of income and workplace inequality," said Sam Smethers, chief executive at the Fawcett Society.
"If we introduced a carer's top up for pension contributions and lowered the threshold so that more low paid women in part-time work could benefit, that could make a real difference."