It takes shoppers queuing at a checkout a maximum of three minutes, or 12.5% of the time spent shopping, whichever is the lowest, to display signs of 'till rage', according to research.
The national survey of shopping behaviour by Envision Retail also says impatient customers in supermarkets frequently trade down from trolleys to baskets to get out quicker.
Envision observed 3,000 people during 300 visits to stores, and noted 52% of shoppers becoming irritated when queuing, although this varied between retailers from 26% to 92%.
Customers with medium-sized baskets have the shortest fuses, with 60% of them showing grumpiness.
Envision said shoppers choose queues based on the number of people in them, but once in the queue they judge it based on time in it.
Men spend 67% less time in store than women and so become ruffled in a shorter time when queuing.
Jason Kemp, Envision Retail MD, said: "Most retailers base their commercial decisions around EPoS and till roll data but we calculate that this o?nly provides about 7% of the information they really need as it just covers what has been bought, where and when. It is important to study how consumers behave rather than ask them to describe how they shop, for generally there is no correlation."
Tesco and Asda are trialling infrared queue technology to monitor queuing times. The systems can display an estimated waiting time to shoppers.