The Prime Minister guessed that a "value sliced white loaf" would cost "well north of a pound", when he was quizzed about the cost of living on LBC 97.3 Radio.
Told by presenter Nick Ferrari that the true cost was around 47p, he revealed that he prefers to use an electric breadmaker - and even gave a plug for the manufacturer of the one he uses.
"I don't buy the value sliced loaf, I've got a breadmaker at home which I delight in using and it turns out in all sorts of different ways," he said.
"But you can buy a loaf in the supermarket for well north of a pound."
Told the true price, he added: "I don't buy the...look I'm trying to get my children to eat the sort of granary - and they take it actually, they like my home made bread.
"A little plug for the flour made in my constituency - Cotswold Crunch - you get some of that, beautifully milled in the Cotswolds, you pop that in your breadmaker. You set the timer overnight so when you wake up there is this wonderful smell wafting through your kitchen.
"It takes 30 seconds to put in the ingredients.
"I'd recommend the Panasonic. There you are, that's a shameless plug. Very easy - even Nick Ferrari could work a Panasonic bread maker."
It came after Mayor of London Boris Johnson admitted he didn't know the cost of a pint of milk.
He told Newsnight's Jeremy Paxman it was "about 80p or something like that".
Told it was half that, he conceded: "Well there you go, I don't know how much a pint of milk costs. So what?"