Around 10 million UK residents could retire with £15,000 less in their pension pots if the government abandons the pension dashboard.
New research on government data from campaign group 38 Degrees suggested there will be 49.6m inactive pension pots worth £757bn by 2050.
Dividing £757bn by 49.6m leaves an average pot size of around £15,000.
38 Degrees campaign manager Lorna Greenwood said: "This research proves that millions of people stand to lose hard earned savings if the government breaks its promise to provide the pensions dashboard.”
The campaign group is holding a petition addressed to Secretary of State for Work and Pensions, Esther McVey, who was reported to be preparing to halt government involvement in the dashboard, which has gathered more than 174,500 signatures.
Greenwood continued: "There is huge public concern over how difficult it is for ordinary people to keep track of their pensions. Millions of people will face impossible decisions during old age like whether to eat or heat their homes.”
The Department for Work and Pensions says that a total of 12m people are not saving enough in their pension schemes for retirement.
Greenwood concluded: “Two years ago the government promised to provide a website by 2019 that would help keep track of their hard earned pensions. They now need to honour that promise and deliver the pensions dashboard on time."