The research, which was carried out in partnership with media owners Clear Channel, JCDecaux and Global, showed an online sales multiplier of 1.7, meaning for every £3 spent in-store due to OOH, £2 is spent online.

The research is based on a nationally representative sample of 2,000 UK adults, with those with a smartphone or tablet completing an online survey on spending habits for both in-store and online purchases across a range of fast-moving consumer goods (FMCG) categories.

Using this data on purchasing habits, an online sales multiplier was created, predicting the additional online sales made when in-store sales are known.

Cosmetics ( 1.83 ), personal care ( 1.75 ), health and wellbeing ( 1.76 ) and clothes categories ( 1.76 ) had the highest online multiplier, according to the research. 

Younger audiences also had a higher online multiplier, averaging 1.81 among 18 to 34-year-olds compared to 1.66 for those aged over 35.

Around 60% of all online spend took place when people were out and about, the research team said.

Tom Jameson, part of the team who carried out the research at GroupM OOH, said: “For retail and FMCG brands, this research highlights how understanding your category’s multiplier can help shape your marketing strategy, enabling you to optimise OOH environments and creative messaging to boost sales – whether that’s through clicks or in bricks and mortar stores.”