Loose Change, Big Latte: How Small Denominations Drove Impulse Buys at a Coffee Chain
A real-world example of Denomination effect in action
Context
BrewLine, a regional coffee chain, runs hundreds of high-traffic locations and tests small operational changes with A/B pilots. Management was exploring low-cost ways to increase the attach rate of pastries and snacks at the point of sale.
Situation
As part of a 12-week A/B pilot across 40 stores, half of the stores instructed cashiers to return customer change using multiple small denominations (coins and $1 bills) while the other half gave change primarily in larger denominations (single $10/$5 bills) or exact card refunds. Cashiers followed a simple script and recorded whether a customer made an additional purchase after receiving change.
The bias in action
Customers who received their change in many small coins and $1 bills behaved as if that money was more 'available' and separate from their main spending account—several customers joked about having 'spare change' and immediately used it to buy a pastry or bagel. In contrast, customers handed a single $10 bill were more likely to mentally integrate that money into their main cash balance and decline an add-on. The presence of multiple small notes/coins increased the salience of 'disposable' money and lowered the psychological barrier to make a low-cost impulse purchase. Cashiers observed and logged multiple cases where customers counted small bills/coins and then said, 'Might as well get a muffin.'
Outcome
Stores that returned change in small denominations saw a measurable lift in add-on purchases: an 8.7% higher attach rate for pastries and snacks versus stores using larger denominations. Over the 12-week pilot, that lift produced approximately $98,400 in incremental revenue across the pilot stores, with an average incremental revenue per participating store of about $2,460 for the period. Customer satisfaction scores did not decline measurably.
What's inside the full case study
Unlock the deeper breakdown with real-world impact, measurable effects, lessons learned, better-approach recommendations, and relevant fields.
Want the full analysis?
Request access to the complete case study, including measurable impact, lessons learned, and the recommended better approach.