A laser tag vest dies mid-game exactly once before you start tracking this. Battery runtime is a fixed number of minutes; a Saturday is a much larger number of minutes. Divide one by the other, round up, and subtract the charge the vest started the day with — that is how many times someone has to walk the arena with a fresh pack.
A 32-game Saturday at 12 minutes a game is 384 play minutes. On a 240-minute pack that is 2 charges, so 1 swap mid-day.
The example
Three kinds of day in the same arena, with the same vests and the same 240-minute packs.
| A | B | C | D | E | F | G | |
|---|---|---|---|---|---|---|---|
| 1 | Day type | Games | Min/game | Runtime min | Play min | Charges | Mid-day swaps |
| 2 | Weekday | 14 | 12 | 240 | 168 | 1 | 0 |
| 3 | Saturday | 32 | 12 | 240 | 384 | 2 | 1 |
| 4 | Holiday | 46 | 12 | 240 | 552 | 3 | 2 |
The formula
Play minutes first, then whole charges, then the swap count:
How it works
Three steps, and the last one is the one people forget:
B2*C2is the day in minutes of actual play. Count scheduled game slots, not open hours — a vest sitting in the rack between groups is not draining at the same rate./D2converts minutes into packs. Runtime is the manufacturer figure minus a safety margin; a pack rated 300 minutes new is realistically 240 after a season.ROUNDUP(...,0)because a vest that needs 1.6 packs needs 2. There is no such thing as running six-tenths of a battery.-1because the first charge is already in the vest when the doors open. Charges minus one is the number of times a staff member has to interrupt the floor.
Multiply swaps by vests to size the charging bank. Twenty vests needing one swap each is twenty packs on chargers by mid-afternoon, not twenty packs total.
Try it: interactive demo
Enter the games booked, the game length, and your realistic pack runtime.
Variations
Packs on the charger
Multiply swaps by the vest count to size the charging bank — and remember a pack coming off the floor is not ready for two hours.
Longest run before a swap
Divide runtime by game length and round down to get how many consecutive games one pack survives. This is the number the floor staff actually memorise.
Pitfalls & errors
Nameplate runtime is optimistic and gets worse with age. Measure a mid-life pack on a busy day and use that number; the difference between 300 and 240 minutes is a whole extra swap on a Saturday.
Charge time, not runtime, is usually the real constraint. If a pack takes three hours to charge and gets swapped every four, you need two packs per vest in rotation, not one spare.
Do not forget to subtract the starting charge. Rounding up to 2 charges and then buying 2 spare packs per vest doubles the battery budget for no reason.
Practice workbook
Frequently asked questions
Why round up instead of to the nearest charge?
Should I count briefing time as play minutes?
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