Experts at Altus Consulting looked at the most popular on-line pension illustration tools from some of the top insurance and wealth management companies.
They calculated what a person was likely to get at the point of retirement, using the example of someone earning £29,360 with existing savings of £37,400 at age 42 with pension contributions of 9.4% from salary.
The results highlighted a "massive disparity in the potential size of the pot at retirement" with the most pessimistic provider quoting just over £115,000 and the most optimistic quoting a little under £370,000. The Money Advice Service calculator was one of many that were tested.

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Despite the recent pension changes coming into force in April none of the tools considered anything other than an annuity for retirement income.
Nearly a third of the providers did not offer the option of calculating how much could be taken as a lump sum at retirement.
Richard Phillips, consultant at Altus, believes that the average person is already confused about how much they need to save for retirement and argued these tools makes matters worse.
He said: "Our own independent research has brought this troubling issue to our attention. The lack of standardisation in this area makes the already complicated world of pension savings a mine field for the average person.
"I would prefer to see tools concentrate on giving guidance on how much people should be saving now to meet their desired pension goals rather than speculating wildly on how much or how little a pension pot might be worth in 25 years time."
Most of the tools indicated what they considered to be the most likely growth rate for the investments but this value varied from below 1.5% for one provider to over 7% for others. The values for the likely income at retirement ranged from a little over £10,000 a year after taking a lump sum of just over £36,000 to £25,000 per year after taking a lump sum of nearly £60,000.
Mr Phillips said: "These current set of tools with their misleading calculations may dissuade people from saving as much as they should into their pensions. We have a great opportunity to produce a generation of savers and given the right tools we can nudge behaviours in the right direction."