# How to set timed entry slots and capacity

> Timed entry is two numbers, not one: how many people the building holds at once and how long a visit lasts. How to turn them into places per slot, what a slot holds while a guest pays, where members and groups fit, and a worked example.

*Source: https://itravel.cloud/blog/timed-entry-slot-capacity · published Nov 1, 2026 · topic: Attractions & venues*

Set timed entry from two numbers you already know: how many people the building may hold at once, and how long a visit lasts. Divide the visit by the slot length to find how many entry groups are inside together, then divide the building's limit by that. The answer is your places per slot. Then decide what holds a place while someone pays, and who comes in outside the slots.

## What a slot controls, and what it does not

A timed entry slot limits **arrivals**: how many people may come in at 10:00, at 10:30, at 11:00. Your building's limit is about how many people are **inside** at the same moment. The fire certificate, the conditions in a gallery and the comfort of a visit are all written in that second number.

The two meet through the length of a visit. A slot limit is only safe for the visit length you assumed when you set it, so the first job is not in any software: it is finding out, honestly, how long people stay.

## Slot length against the length of a visit

The arithmetic is short:

- **Groups inside at once** = visit length ÷ slot length, rounded up.
- **Places per slot** = building limit ÷ groups inside at once.

Use the visit length most guests are finished by, not the average. An average hides the families who stay twice as long, and they are the people who take you over the limit on a Saturday afternoon. Scan guests in and out on a few busy days and read the time between the scans, or time a sample by hand.

Slot length is then a decision about the queue, not about capacity:

| Slot length | What it does at the door | Suits |
|---|---|---|
| 15–20 minutes | Small, steady arrivals; more times to choose from | Small rooms, a single narrow entrance |
| 30 minutes | Easy for guests to remember | Museums, aquariums, observation decks |
| 60 minutes or more | Larger waves; fewer, simpler choices | Long visits, large or outdoor sites |

Shorter slots do not let you sell more. Halving the slot halves the places per slot and doubles the number of slots; the number inside stays the same. What changes is the size of each wave at the door.

## A worked example: 300 at a time, 30-minute slots

Say a museum may hold 300 people at a time, opens at 09:00 and closes its doors at 17:00. Visits last 90 minutes. Entries every 30 minutes.

90 ÷ 30 = 3 groups inside at once. 300 ÷ 3 = **100 places per slot**.

Follow the day, assuming everyone stays exactly 90 minutes:

| Clock | Entry groups inside | Inside at 100 a slot | Inside at 90 a slot |
|---|---|---|---|
| 09:00 | 09:00 | 100 | 90 |
| 09:30 | 09:00, 09:30 | 200 | 180 |
| 10:00 | 09:00, 09:30, 10:00 | 300 | 270 |
| 10:30 | 09:30, 10:00, 10:30 | 300 | 270 |
| 15:30 (last entry) | 14:30, 15:00, 15:30 | 300 | 270 |
| 16:30 | 15:30 | 100 | 90 |

Three things come out of that table.

**The last entry is not the closing time.** A guest who enters at 16:30 for a 90-minute visit is still inside at 18:00. With the doors closing at 17:00, the last entry worth selling is 15:30.

**The visit length is a floor, not a promise.** If many visitors really need 120 minutes, four groups overlap, not three, and 100 a slot puts 400 people inside. Planning on 120 minutes gives 300 ÷ 4 = 75 a slot.

**Leave room for people who arrive outside the slots.** If up to 30 members come in on their cards during a busy 90 minutes, take them off first: (300 − 30) ÷ 3 = 90 a slot, the right-hand column.

At 90 a slot from 09:00 to 15:30 there are 14 entry times and 1,260 tickets on a full day: 180 arrivals an hour, or three people a minute through the entrance. Check that against how fast your door really admits people. A plan the entrance cannot keep up with becomes a queue that eats the next slot.

## What a slot holds while a guest pays

Between "choose a time" and "payment confirmed", a place is neither free nor sold. Ignore that state and two guests can pay for the last place. Hold it too long and a slot looks full when it is not.

The shape that works:

- **A hold** takes the places when the guest picks a time, with an expiry. The check and the hold are one step, so nobody is sold a place someone else is holding.
- **Expired holds go back by themselves**, so a basket abandoned on the payment page does not keep a slot full.
- **Paying turns the hold into a sale.** A payment that arrives after the hold ran out tries to take the places again; if they have gone, that order must land in front of a person.
- **Several tickets are held together or not at all.** A family of five never ends up with three places.

## Members, groups and walk-ups in the same building

Everyone inside counts against the same 300, however they bought.

**Members.** Decide whether members book a time or simply walk in. Walking in is friendlier, and it is why the example holds places back; booking is safer on peak days. You can do both: the card on quiet days, a member-price timed ticket on the days you expect to fill.

**Groups and schools.** A group of 40 is 40 places in one slot. Sell it as one order so its places are held together, and decide how much of any slot groups may take: two coaches at 10:00 can leave nothing for anyone else.

**Walk-ups.** The box office sells from the same count as the online shop, so a walk-up gets whatever the shop has not sold.

**A timed room inside.** If a day ticket includes a special exhibition with its own limit, sell the room alone and inside the ticket from one count, or the two will oversell it between them.

## Early and late arrivals

A guest booked for 10:00 arrives at 09:40. Another arrives at 11:15. Your policy decides what happens, and staff should be able to say it in one sentence.

| Policy | How it feels at the door | What it costs |
|---|---|---|
| Only within the slot | Fair and predictable | Arguments at the door; staff become enforcers |
| A short margin either side | Forgiving, still predictable | Small overlaps with the next group |
| Any time on the day | Easiest at the door | The slot limits arrivals only on paper |

Both directions move the count. An early guest arrives on top of a group still inside; a late one stays on into later groups' time. A margin of a few minutes changes little. A margin of an hour turns your slots into a suggestion, and your places per slot should then be lower.

## Which model to choose

| Situation | Choose | Why |
|---|---|---|
| Long, free-flowing visits (a zoo, a park) | Day admission with a daily limit | Arrival times matter less than the day's total |
| A hard building limit and a visit of predictable length | Timed entry | Spreads arrivals so the inside count stays under the limit |
| Everyone starts and ends together (a show, a tour, a cruise) | Sessions with a length | The limit is the room, the boat or the guide |
| A timed room inside a day ticket | The room as its own timed product, included in the ticket | One count for both ways of buying it |

## How iTravel Attractions handles timed entry

Attractions is [ticketing and day-running software for venues](/attraction-ticketing-software) of every kind. For timed entry it works like this.

- **Three ways in.** A ticket is day admission (a daily limit, valid until closing), [timed entry](/timed-entry-ticketing) (an entry time every 15, 20, 30, 60, 90 or 120 minutes, a limit per time) or sessions (named start times with a length). Choosing a kind fills in a starting point you change: an aquarium starts as timed entry every 30 minutes, a museum as a day ticket.
- **The limit is per entry time.** Entry times run from your opening time up to, but not including, the closing time you give, so give it the time just after your last entry (16:00 for a 15:30 last entry), not the time the doors close. The building limit is your arithmetic; the gate's "inside now" shows the result.
- **Holds.** Picking a time holds the places for 15 minutes, every ticket in the basket in one hold, all or nothing. A hold is one conditional update on that time's row, so two buyers cannot both take the last place: in a proof run, 2,016 attempts to hold places on one 300-place time took exactly 300. One buyer may have at most three unpaid orders open at a venue. A box office sale takes and sells its places in one step.
- **A late payment** takes its places again if they are still free; if not, the order shows on Today as needing a person, and you refund it. The slot is never oversold.
- **The shop** shows what is left at each time. A full time cannot be picked, and a time that has already started is no longer sold.
- **Changing the limit never un-sells.** A new limit below what is already sold leaves nothing more to sell; the bookings stay.
- **The calendar** colours each day by how full it is and opens each time on its places, sold, held, blocked and left. A time can be closed from there for weather ([closing for weather](/blog/weather-closures-attractions)).
- **Members** come in on their card and the visit is counted, but the card takes no place from an entry time; a timed ticket bought at the member price does ([memberships and annual passes](/blog/attraction-membership-annual-pass)).
- **A timed room inside a ticket** takes its times and places from a timed product of the same venue, so the room sold alone and the room included in day tickets share one count. There the gate lets a ticket in from 15 minutes before its time until an hour after. Parts of a ticket across several venues each take their own places ([combo tickets](/blog/combo-tickets-across-attractions)).
- **At the main entrance** the gate phone checks the day, not the minute, so holding guests to their time is your staff's call ([what the gate checks](/blog/offline-ticket-scanning)).

## Set-up checklist

- Measure the visit length most guests are finished by, on a busy day.
- Write down the building's limit, and that of any room inside with its own.
- Work out groups inside (visit ÷ slot) and places per slot ((limit − people outside the slots) ÷ groups inside).
- Set the last entry: the closing time less the visit length.
- Decide members: walk in on the card, book a time, or both by day.
- Decide how much of a slot groups may take, and check it each time you take a group booking.
- Write the early and late arrival rule in one sentence and give it to the gate team.
- Check arrivals per half hour against how fast your entrance admits people.
- After the first busy weekend, compare "inside now" with your plan and adjust the limit. Lowering it never cancels anyone already booked.