Earlier this week, Morrisons launched a twelve-inch version of the pastry favourite, which is believed to be the largest sausage roll on sale at any UK supermarket.
But an eagle-eyed glutton noticed his first roll seemed longer than a foot, so bought five more and measured them.
The five of the jumbo rolls were brought from the Morrisons store in Chalk Farm, north London, and all of which measured thirteen inches, an inch longer than the advertised length.
The hungry bloke, who asked not to be named, said: "Blokes like me are famously bad at judging lengths in inches.
"I was very hungry so decided to pick one up and split it in half. When I picked up the second half, to my eye it looked bigger than six inches.
"I had a fiver on me so I decided to buy some more and measure them - I was stunned but delighted that they all measured 13 inches.
"It's not often in this day and age you get something for nothing."
Produced in the UK, the rolls contain 26 per cent pork and 1650 calories, equivalent to three Big Macs and only 350 calories less than a woman's daily intake.
Retailing at just £1, it was created after customers had asked for an even bigger version of the traditional sausage roll.
Conveniently, it was launched in time for the football season, with Morrisons hoping it will become the ultimate match day experience.
Freshly baked in store, it is believed to be double the length, and four times the weight of of other high street competitors.
It also requires a special tray as opposed to a paper bag, just to hold the weight of it.
A Morrisons spokesperson said: "At Morrisons we always go the extra mile - and in this case the extra inch.
"It's just how we roll."