If their preferred product was unavailable, over a third (37%) of shoppers would go to another store, 6% would buy nothing at all and 19% would switch to a rival brand, reveals the research.
However, the risk of dissatisfied shoppers switching to a rival's store permanently had been overplayed, suggests IGD. Only 2% of shoppers claimed they would switch to a rival for their main shop if faced with persistent out of stocks, with factors such as familiar store layouts, accessible locations and favourable prices seen as being more important.
The research also revealed that poor merchandising or frequent changes to layout meant retailers were missing out on sales as customers could not find products quickly and assumed they were out of stock. Walls of similar products were also found to be confusing, with many shoppers passing them by altogether.
IGD's Joanne Denney-Finch said: "With almost half of shoppers claiming to experience out of stocks, retailers and manufacturers stand to lose significantly as a result of shoppers' responses to these situations."
The research was conducted in January-February with 1,000 shoppers.