What does the research show?
The best-known study comes from a campus café, by Kivetz, Urminsky and Zheng (2006), summarised in the Chicago Booth Review. Customers earned a free coffee after ten purchases. Two findings help you right away:
- The closer the reward came, the faster they returned. Time between purchases shrank by about 20 percent from the first stamp to the last.
- An empty 10-stamp card took 15.6 days to finish. A 12-stamp card with two free stamps took 12.7 days, even though both needed ten purchases.
The limit: the study didn't compare different stamp counts, and these were customers of one campus café. It won't give you the perfect number for your business. It does show that being close to a goal motivates people.
How do you work out your number?
Ask two questions: how often does a typical regular come, and what does the reward cost you? Here's a made-up example, Café Morgenrot, with a 4 euro cappuccino.
| Stamps | Full after, at 2 visits a week | Full after, at 1 visit a week | Discount per purchase, on paper |
|---|---|---|---|
| 6 | 3 weeks | 6 weeks | 67 cents |
| 8 | 4 weeks | 8 weeks | 50 cents |
| 10 | 5 weeks | 10 weeks | 40 cents |
| 12 | 6 weeks | 12 weeks | 33 cents |
Our rule of thumb, not a study: a regular should fill the card in four to six weeks. So for guests who come twice a week, eight to twelve stamps fits. If they come once a week, ten is already a lot. Six fits the rule, and eight is still fine.
How do you use the free stamp trick?
Give people a head start rather than a shorter card. At Café Morgenrot, that would mean twelve boxes with two already stamped. It costs you no extra coffee and feels like a gift.
Also define the reward exactly. "One hot drink up to 5 euros" is clearer than "a drink". If you want more variety, offer two steps on one card, such as a biscuit at five and a coffee at ten. Then the first reward comes early.
How do you set this up on a digital card?
In the NFCeez app you set up to three rewards, each at its own stamp, such as a biscuit at three and a coffee at ten. The head start from the study is there as welcome stamps: new guests get extra stamps on their first visit. Later the app shows how many guests are just one stamp away. You can change the rewards at any time, and collected stamps stay. The limit: you still work out the right number yourself with the table above. More on the digital stamp card.
Whether the whole thing pays off is in our short answer, and the full plan is in restaurant loyalty programmes.
Your next step: ask three regulars tomorrow how often they come each week, and pick the number from the table.
How NFCeez does thisUp to three rewards, and a head start.Set which stamp earns what, and give new guests extra stamps on their first visit. The app then shows you who is just one stamp away.See how it works
