The pensions dashboard will need to be fit to handle up to 15 million users when it goes live next year, technology provider Origo has said.
The provider-owned fintech company warned the underlying infrastructure will need to be able to cope with both, visits to the dashboard and external requests made through third party apps.
It based its analysis primarily on Statista UK age demographics and Pension Policy Institute analysis but said it was close to what it had expected from discussions with providers, such as banks.
Parliamentary under-secretary of state for pensions and financial inclusion, Guy Opperman, has committed to launching the pensions dashboard by the end of 2019.
The dashboard will enable savers to see all of their retirement pots in one place at the same time, giving them a greater awareness of their assets and how to plan for their retirement.
But there has been discussion about the shape the project should take, whether it should be a single or multiple dashboards, and whether advisers should be given access to their client's dashboards.
Anthony Rafferty, managing director at Origo, said: "Whether there is one or multiple dashboards from launch, as is still being debated, the underlying infrastructure must be flexible to cope with future technological requirements.
"Over time, demand for the service can only grow as more people join workplace pensions, particularly through auto enrolment, and those also wishing to check on their state pension.
"Engendering and demonstrating trust and reliability to users will determine the success of the pensions dashboard."
Earlier this month the Work & Pensions select committee recommended the implementation of a single dashboard.
The MPs said the case for multiple dashboards hosted by "self-interested providers" was "far less convincing" as it would add more complexity where simplicity was needed.
Ricky Chan, director at IFS Wealth and Pensions, sympathised with the committees views on having a single dashboard.
He said: "I would have thought the whole point of the pensions dashboard was to simplify things and help the clients understand what pensions they hold. I can't understand why multiple dashboards would exist. Surely this would create more problems and red tape and confusion for everyone involved?"
But Nathan Long, senior pension analyst at Hargreaves Lansdown, criticised this idea.
He said: "Open banking has put people firmly in control of elements of their own finances, yet pensions are not seemingly being treated with the same urgency. People will struggle to make confident retirement planning decisions without innovation."
Origo, which has been developing the underlying technology for a number of dashboard prototypes, said experience in other European countries, which already have dashboards in place, showed increasing external demand for APIs to access consumer pension data from fintechs, which in turn was driving an increase in usage.
The firm also advocated adviser access to the dashboard.
Origo told FTAdviser last October it was confident it could deliver the technology to give advisers access from the start should it get chosen as the firm to run the underlying processes for the project.