Around one in eight people believe their energy bill will fall before the end of the year, according to new research.
A survey of more than 2,000 adults found just 8% predicted costs would rise by £1,500 when the price cap is raised by regulator Ofgem in October – despite experts estimating that to be the expected increase.
Most thought their charges would go up by around £487, the USwitch poll found, around a third of actual predicted rise.
About 12.5% of those asked thought theirs would reduce, though more than a quarter said they did not know what is likely to happen to the price.
Current plans were announced in May when the price cap was expected to reach around £2,800 in October.
It is now thought to be £800 higher than that in October, and could reach as high as £5,000 in April.
Earlier this month, Ofgem confirmed that the energy price cap will be updated quarterly, rather than every six months, as it warned that customers face a very challenging winter ahead.
USwitch director of regulation, Richard Neudegg, said: “The new predictions will leave a lot of people worried about how they are going to afford their bills this winter and beyond, based on the sky-high predictions through to next October.
“Households desperately need to know that sufficient financial support will be provided.”
The research asked households across the UK to estimate their energy costs and predict how much they would rise in the future.
The Government announced £400 for every household in May, which will be paid in six instalments. It also promised support of up to £1,200 for more vulnerable people.
“The promised £66-a-month over winter, while a good start, will barely touch the sides of the predicted increase,” Mr Neudegg said.
“The energy bill support needs to be urgently reviewed.
“If you are worried about your bill payments, or your energy account is going into debt, speak to your provider as soon as possible.
“They should be able to help you find a way forward, such as working out a more affordable payment plan.
“You may also find you are eligible for additional support such as hardship funds and other energy help schemes.”