How many stamps should a loyalty card have?
Ten is the default because it is a round number, not because it is right. The correct answer falls out of two things you already know: what one visit earns you, and how often your regulars actually come in.
Start from the giveaway rate, not the stamp count
A card that gives a free coffee on the tenth stamp is giving away roughly 10% of what a member buys. That is the number that matters, and you can set it directly: divide the reward's value by the discount you are willing to fund.
If a flat white costs you €0.80 in goods and sells for €3.20, and you are happy giving away about 8% of member revenue, the card needs roughly twelve stamps. If you are happy at 12%, eight stamps. The stamp count is an output.
Most independent cafés land somewhere between 8 and 12 for coffee. Higher-ticket businesses — a salon, a treatment room — usually want fewer stamps and a bigger reward, because a customer who visits once a month will not fill a ten-slot card inside a year.
Then sanity-check it against visit frequency
A card only works if a member can realistically finish it while they still care. The rule of thumb: a member should be able to complete the card in about two to three months at their normal rate.
- Twice a week (a commuter café): 10-16 stamps is comfortable.
- Once a week (a neighbourhood bakery): 8-12.
- Twice a month (a salon, a barber): 5-8.
- Once a month or less (a spa, a garage): a stamp card is the wrong tool. Use a prepaid package or a tier instead.
If your maths from the first section says twenty stamps and your customers come in fortnightly, the card takes ten months to finish. Nobody is still thinking about it in month seven. Lower the reward instead of raising the stamp count.
Give the first stamp away
A card at 0 of 10 looks like a chore. A card at 1 of 10 looks like something already begun, and people finish things they have started. This is the one piece of loyalty psychology that is both well-evidenced and free to apply.
In practice: add one stamp at signup and add one to the requirement. A card at 1 of 11 costs you exactly what a card at 0 of 10 costs, and completes more often.
What to do when you get it wrong
You will, and it matters less than it feels like. Changing a card's requirement changes it for everyone, including members mid-card — so when you shorten a card, some members will unlock a reward immediately, and that is fine. It is a good day for them and a cheap apology from you.
Lengthening a card is the one to be careful with. A member who was one stamp away and is now three away will notice. If you need to make a card harder, it is usually better to leave the existing card alone and launch the new terms alongside it.