“Ace the 18th, play free” feels like it costs nothing until you count how many people ace the 18th. Expected cost is just three numbers multiplied: how many rounds, how often the prize is won, and what the prize is worth to you.
4,200 rounds with a 1.8% ace rate on a $12 free game is $907.20 a month — a real line item, not a rounding error.
The example
Three promotions running on the same 4,200 monthly rounds, each with its own win rate and prize value.
| A | B | C | D | E | |
|---|---|---|---|---|---|
| 1 | Promotion | Rounds | Win rate | Prize value | Expected cost |
| 2 | Free game replay | 4200 | 1.8% | $12.00 | $907.20 |
| 3 | Prize wall pick | 4200 | 0.9% | $5.00 | $189.00 |
| 4 | Season pass | 4200 | 0.05% | $60.00 | $126.00 |
The formula
One multiplication, rounded to cents:
How it works
Each factor answers a different question:
B2is exposure — how many chances at the prize you hand out. Count rounds, not players, unless the prize is per group.C2is the win rate, entered as a percentage. Track it from your own scorecards; published ace rates for a given hole vary enormously with hole design.D2is the prize value at your cost, not retail. A free round costs you the marginal cost of a round, not the ticket price, unless the course is at capacity.ROUND(...,2)lands it in dollars and cents for the budget.
Sum the column and you have the monthly promotional reserve. Compare that to the extra rounds the promotion drives before deciding it is worth running.
Try it: interactive demo
Enter monthly rounds, the win rate, and what the prize costs you.
Variations
Cost per round played
Divide the expected payout by rounds to see the per-ticket drag.
Worst month, not average
Budget a cushion above the mean for a bad run of luck.
Pitfalls & errors
Expected cost is an average, not a cap. A promotion with a $500 prize and a 0.1% win rate averages cheap and occasionally costs you $500 in a single week — if the prize is large, cap the number of winners in the rules.
Win rates rise when players know the prize exists. Measure the ace rate after the sign goes up, not before — people take a lot more shots at a hole that pays.
Do not use retail value for a free-round prize. If the course has empty capacity, the true cost is the marginal cost of the round, and using the ticket price overstates the liability several times over.
Practice workbook
Frequently asked questions
What is a realistic hole-in-one rate on a mini golf hole?
How is this different from just tracking prizes paid?
Stop fighting formulas. Learn them in a day.
This recipe is one of hundreds of real-world formulas we teach. Our Excel Formulas & Functions class covers lookups, logic, text, and dynamic arrays hands-on — live in Dallas–Fort Worth, Houston, Austin, Oklahoma City, Denver, or online.
See the Formulas & Functions Class