# Chat pricing

How Chat SDK features contribute to your message count and strategies to optimize costs.

The [Chat SDK](https://ably.com/docs/chat.md) is built on top of [Pub/Sub](https://ably.com/docs/pub-sub.md). All Chat operations generate Pub/Sub messages that follow the same counting rules.

## Chat operations 

The following table shows how Chat operations contribute to your message count:

| Operation | Messages counted |
| --- | --- |
| [Messages](https://ably.com/docs/chat/rooms/messages.md) ||
| Send message | 1 inbound message |
| Message delivery | 1 outbound message per subscriber |
| Update message | 1 inbound message |
| Message update delivery | 1 outbound message per subscriber |
| Delete message | 1 inbound message |
| Message deletion delivery | 1 outbound message per subscriber |
| [History](https://ably.com/docs/chat/rooms/history.md) ||
| History retrieval | 1 outbound message per retrieved message |
| [Typing indicators](https://ably.com/docs/chat/rooms/typing.md) ||
| Typing keystroke | 1 inbound message; repeats every heartbeat interval (default 10s) |
| Typing keystroke delivery | 1 outbound message per subscriber per heartbeat |
| Typing stop | 1 inbound message |
| Typing stop delivery | 1 outbound message per subscriber |
| [Room reactions](https://ably.com/docs/chat/rooms/reactions.md) ||
| Room reaction | 1 inbound message |
| Room reaction delivery | 1 outbound message per subscriber |
| [Message reactions](https://ably.com/docs/chat/rooms/message-reactions.md) ||
| Message reaction send | 1 inbound message |
| Message reaction delete | 1 inbound message |
| Message reaction summary delivery | 1 outbound message per subscriber; multiple reactions may be rolled up into a single summary |
| [Presence](https://ably.com/docs/chat/rooms/presence.md) ||
| Presence enter | 1 inbound message |
| Presence leave | 1 inbound message |
| Presence update | 1 inbound message |
| Presence event delivery | 1 outbound message per presence subscriber |
| [Occupancy](https://ably.com/docs/chat/rooms/occupancy.md) ||
| Occupancy event | 1 outbound message per subscriber (generated on membership changes, debounced up to 15s) |
| [Moderation](https://ably.com/docs/chat/moderation.md) ||
| Moderation rule invocation (before or after publish) | 1 outbound webhook event per moderated message |

## Rooms and channels 

Each Chat [room](https://ably.com/docs/chat/rooms.md) is backed by a single Ably Pub/Sub channel. All room features, such as messages, typing, reactions, presence, and occupancy, share that one channel.

Channels contribute to your [channel count](https://ably.com/docs/platform/pricing.md#channels). The more rooms a client is attached to, the more channels are consumed. [Detach](https://ably.com/docs/chat/rooms.md#detach) from rooms when they are no longer needed, and [release](https://ably.com/docs/chat/rooms.md#release) rooms that are no longer in use to reduce your channel count.

## Connections 

Ably bills each connected client for [connection minutes](https://ably.com/docs/platform/pricing.md#connections). A connection-minute is counted for every minute a client maintains an open connection, regardless of activity. Clients that remain connected but idle still accrue connection minutes. Close connections when the client is done to stop accruing connection minutes.

## Cost optimization 

### Reduce typing indicator frequency

Increase the `heartbeatThrottleMs` [room option](https://ably.com/docs/chat/rooms.md#typing) to reduce typing indicator event frequency. The default is 10 seconds. Increase this value in rooms that tolerate delayed typing feedback.

### Use server-side batching

[Server-side batching](https://ably.com/docs/messages/batch.md#server-side) groups messages into single deliveries. Use this for high-throughput rooms where slight delay is acceptable.

### Use occupancy instead of presence

Use [occupancy](https://ably.com/docs/chat/rooms/occupancy.md) instead of [presence](https://ably.com/docs/chat/rooms/presence.md) when you only need member counts, not individual identities.

## Documentation Index

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