# How shared-capacity sessions work

> Sell spaces in one shared session instead of 1:1 appointments, so many customers book the same time slot up to the capacity you set.

Many customers book into the same time slot, each taking one of a fixed number of spaces. Unlike an appointment app, where one customer gets the whole slot, your 6pm session takes bookings until its spaces run out. Session prevents overbooking and shows customers how many spaces are left.

<Screenshot
  shot="shared-capacity-editor"
  mat="sage"
  alt="The session editor with the Capacity field set, showing how many spaces a single session holds"
  caption="Set capacity per session in the session editor."
/>

## Spaces, not appointments

A space is one place in the room - the unit your capacity is measured in. Each booking takes one or more spaces, so a 10-space session could be ten people booking one each, or one person booking four and others filling the rest. When the last space goes, the session shows as full and stops taking bookings.

## Set capacity per session

<Steps>
  <Step>Open [the Sessions page](/go/admin/sessions) and create or edit a session.</Step>
  <Step>Set **Spaces available this session** to the number of people the room comfortably holds, then save.</Step>
</Steps>

## The capacity hierarchy

Session uses the most specific capacity that's set:

1. **Single-session override** - a capacity set on one date wins over everything else. See [override a single session](/docs/instance-overrides).
2. **Schedule capacity** - the **Spaces** field on a time in a [repeat schedule](/docs/repeat-schedules), for every session that time generates. Blank follows the session default. See [different spaces at different times](/docs/repeat-schedules#different-spaces-at-different-times).
3. **Session default** - the capacity on the session itself.

Most venues set it once on the session. Use a time's Spaces field when one slot is always bigger (say a second room opens in the evenings), and a single-session override for the odd day with fewer or more spaces. Lowering capacity below current bookings never cancels anyone - the session just stops taking new ones.

## Overbooking prevention

Session checks capacity at the moment of booking, so two customers can't claim the last space at once. A full session shows as sold out, and a [waiting list](/docs/waiting-lists) appears automatically, emailing customers when a space frees up.

## Group and private bookings

- **[Group bookings](/docs/group-bookings)** let one customer book several spaces while others book the rest.
- **[Private sessions](/docs/private-sessions)** let one customer book out every space.

Both are priced as a single unit and capped to the session's real capacity.

## Limit spaces per booking

By default a customer can book as many spaces as are available. To keep sessions open to more people, click **Limit bookable spaces per person** under the capacity and set **Max per booking**. A single multi-space price like private hire is exempt, since it's sold as one unit.

## Common questions

1. **How do customers choose how many spaces?** Each session on the booking page shows its remaining spaces and a quantity stepper, up to the spaces left and any per-booking limit.

2. **Do shorter bookings share the same capacity?** Yes. With [part-session pricing](/docs/part-session), shorter and longer bookings draw on the same spaces.

3. **Can customers change their booking afterwards?** See [how customers manage their own bookings](/docs/manage-bookings-customers).

Next, build a [repeat schedule](/docs/repeat-schedules), [override a single session](/docs/instance-overrides), or browse all [sessions and scheduling](/docs/category/sessions-scheduling) articles.