Around one in eight people think energy bills will go down this winter, while most underestimate the massive price rises that are likely to come.
New research from Uswitch found that families believe their household gas and electricity bills will go up by £487 from the start of October.
But experts have predicted that bills will rise by more than three times that amount.
The bill for an average household will increase by around £1,600 to over £3,600, according to the most recent forecasts.
More than a quarter of households said they did not know what is likely to happen to the price cap on energy bills, according to the research commissioned by Uswitch. Meanwhile 12% said that they think it will decrease this winter.
Only around one in 13 people (8%) thought that bills will go up by more than £1,500 – which is what experts predict.
“With the summer holidays in full swing, it’s not surprising that so many people haven’t been on top of the news about changes in the price cap,” said Richard Neudegg, director of regulation at Uswitch.
He called for the Government to act quickly to lend more support to households. 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.
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.
“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.
He added: “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.”
Researchers at Opinium polled 2,000 adults across the UK online between July 19 and July 22. They weighted the sample to be politically and nationally representative.
People were asked: “Ofgem are due to review the energy price cap again in August, to implement in October. What do you think will happen to the price of your Standard Variable Tariff in October after the review?”