A double-stamp day pays for itself when it pulls customers into hours that would otherwise sit empty, and it costs you when it lands on a day your regulars were coming anyway. The extra stamp is cheap. What you are really paying for is every reward arriving sooner for everyone who visits in the window, including the people who needed no nudge at all. So run it in your quietest few hours, no more than about once a month, and count before and after: if the margin on the extra sales beats the cost of the stamps you gave away, it worked.
What one extra stamp really costs
Start with the cost of a single stamp. Divide what your reward costs you to supply by the number of stamps on the card. A free coffee that costs $1.40 in beans, milk and cup, on a ten-stamp card, makes each stamp worth 14 cents to you. The customer sees it differently: to them it is a tenth of a $5.20 coffee, about 52 cents. That gap is why stamps feel generous and cost little, as the entry on reward cost explains.
On a double-stamp day every member visit in the window earns one stamp more than usual. The cost of the day is the number of member visits in the window multiplied by the cost of one stamp. It is easy to forget that this includes every regular who would have walked in at that hour regardless. Those extra stamps buy nothing; they simply move the regular's free coffee a little closer.
Do not count on members never filling their cards. A stamp given today is a reward handed over later for nearly everyone who keeps coming.
Three kinds of visit in the window
Every visit during a double-stamp window is one of three kinds.
The first is the customer who would have come at that time anyway. They cost you an extra stamp and bring nothing new.
The second is the customer who would have come at a different time and moved. They also bring no extra sale, though moving them can still be useful if it takes them out of a queue on a busier day.
The third is the customer who would not have come at all. These are the only visits that pay, and the whole job of choosing the window is to make this group large and the first group small. That means a time when the shop is quiet but people are nearby and could be persuaded: the hour after the lunch rush near offices, the school pick-up window near a primary school, a slow mid-week afternoon on a shopping strip.
The sum to do
Here is the break-even test in one line. Extra sales in the window, times the margin on each sale, must be larger than member visits in the window, times the cost of one stamp.
Margin here means the price less the cost of the goods. If you rostered nobody extra for the window, leave wages out, because you were paying them anyway. If you added a person to cope, add their hours to the cost side.
A worked example: Tallowwood Coffee Hatch
Tallowwood Coffee Hatch is a fictional coffee window on the edge of a business park. Its card is ten stamps for a free coffee. A coffee averages $5.20 and costs $1.40 to make, so the margin on each is $3.80. The club has 260 members, all of whom agreed to hear from the hatch by text.
On an ordinary Tuesday between 2 and 4 the hatch sells 22 coffees, 14 of them to members. The owner picks that window, briefs the two staff on shift, and sends one text at half past eleven:
Double stamps on every coffee today from 2 to 4. Say your mobile at the hatch to collect.
The window sells 49 coffees, 37 of them to members, including eight people who joined on the spot. Over the next two days, Wednesday and Thursday afternoons are four coffees down on usual, so four of the Tuesday buyers simply moved.
Extra coffees: 49 less the usual 22 is 27, less the 4 that moved, leaves 23 genuinely new sales. Margin on those: 23 times $3.80 is $87.40.
Cost: 37 member coffees each earned one extra stamp, so 37 times 14 cents is $5.18.
The afternoon cleared about $82 more than an ordinary Tuesday. That is a double-stamp day doing its job.
Now the same owner tries it on a Saturday morning, 8 to 11, when the hatch normally sells 180 coffees, 120 to members. The double-stamp Saturday sells 188, with 128 to members, and Friday and Sunday are three coffees down between them. Five genuinely extra coffees bring in $19 of margin. The extra stamps cost 128 times 14 cents, or $17.92. The morning netted about a dollar, the queue ran longer than usual, and two customers at the back gave up and left.
Finally the owner makes Tuesday afternoons a weekly fixture. For three weeks the numbers hold. By the sixth week the Tuesday window still sells 45 coffees, but Monday and Wednesday afternoons have each lost about ten. The regulars have learned to save their visits for Tuesday. The new sales are gone and the extra stamps are still being given, every week.
When a double-stamp day works
It works in a genuinely quiet window with people close by who could come but usually do not.
It works short and sharp: two or three hours, announced that morning, so there is no time for regulars to rearrange the week around it.
It works rarely, once a month at most, or tied to a real occasion such as the shop's birthday or the first day of a new menu.
It also works as a reason to join. A customer who signs up during the window walks out with two stamps from their first purchase, and a card that is already a fifth of the way to a reward feels worth keeping.
When it costs more than it brings
It costs on your busiest days, when nearly every member visit was coming anyway.
It costs when it becomes a weekly habit, because regulars shift their visits into it.
It costs more on a short card with a dear reward. On a five-stamp card worth $40 off, each extra stamp is $8 of takings, so a boutique needs far more new business to pay for a double-stamp day than a cafe does.
It also costs more on a per-item rule. A customer buying six loaves for a party collects twelve stamps instead of six, and the reward lands two visits early.
Mistakes to avoid
Forgetting the staff. Everyone on shift needs to know the window, the rule and the words to say. In Counter Club there is no double-stamp switch: a double stamp is two presses of Stamp on the member's row, and the rule lives on your sign, as what counts as a stamp explains.
Not counting. Decide before the day what you will measure: sales in the window, sales in the same window over the previous four weeks, and the two days after.
Giving a week's notice. A long run-up lets regulars move visits into the window and defeats the point.
Stacking offers. A double-stamp day on top of a price special is two costs chasing the same customer.
Leaving out the club. Telling members on the day needs a campaign, which comes with a paid plan; on Free, a chalkboard at the door and the sign by the till do the same job for passers-by. The details are on the campaigns page.
What to do this week
- Pull last month's sales by hour from your till and find your two quietest regular windows.
- Work out your cost per stamp: the cost of your reward divided by your target.
- Write down how many sales those windows made in each of the last four weeks.
- Pick one window, brief the staff on shift, and put a sign up that morning.
- Afterwards, count the window and the two days after, and do the sum before deciding on a second one.
If your target is the real problem, and cards feel too far off to bother with, change the card instead; how many stamps a card should have covers that.