# Pub/Sub pricing

How Pub/Sub operations contribute to your message count and strategies to optimize costs.

Pub/Sub operations contribute to your message count based on publishing, delivery, and optional features like persistence and presence.

## Pub/Sub operations 

The following table shows how Pub/Sub operations contribute to your message count:

| Operation | Messages counted |
| --- | --- |
| [Messages](https://ably.com/docs/channels/messages.md) ||
| Publish | 1 inbound message |
| Message delivery | 1 outbound message per subscriber |
| [Presence](https://ably.com/docs/presence-occupancy/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 |
| Presence REST query | 1 outbound message per member returned |
| Batch presence request | 1 outbound message per member across all queried channels |
| [Storage and history](https://ably.com/docs/storage-history/storage.md) ||
| Persistence storage | 1 additional message per stored message |
| History retrieval | 1 outbound message per retrieved message |
| [Rewind](https://ably.com/docs/channels/options/rewind.md) on attach | 1 outbound message per rewound message (up to 100) |
| [Integrations](https://ably.com/docs/platform/integrations.md) ||
| Integration delivery | 1 outbound message per integration target |
| [Inbound integration publish](https://ably.com/docs/platform/integrations.md#inbound) | 1 inbound message |
| [Push notifications](https://ably.com/docs/push.md) ||
| Push notification delivery | 1 outbound message per delivered notification |
| [Annotations](https://ably.com/docs/messages/annotations.md) ||
| Annotation publish | 1 inbound message |
| Annotation delete | 1 inbound message |
| [Annotation summary delivery](https://ably.com/docs/messages/annotations.md#annotation-summaries) | 1 outbound message per subscriber; multiple annotations may be rolled up into a single summary |
| [Metadata and stats](https://ably.com/docs/metadata-stats/metadata.md) ||
| Lifecycle event (`[meta]connection.lifecycle`, `[meta]channel.lifecycle`) | 1 outbound message per event |
| `[meta]stats:minute` event | 1 outbound message per event |
| `[meta]log` subscription | Not counted |

## Channels 

[Channels](https://ably.com/docs/channels.md) are the unit of message distribution. Each channel you use contributes to your [channel count](https://ably.com/docs/platform/pricing.md#channels). Ably includes channels with each package and charges for additional channels beyond the included allowance.

## 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.

## Cost optimization 

### Use ephemeral messages

Mark messages as [ephemeral](https://ably.com/docs/pub-sub/advanced.md#ephemeral) to exempt them from persistence, rewind, resume, and integrations. Use this for streaming data where history is not needed.

### Disable self-delivery

Set [echoMessages: false](https://ably.com/docs/pub-sub/advanced.md#echo) to prevent messages from being delivered back to the publisher. This is useful for optimistic UI patterns and server-side publishers.

### Enable conflation

[Conflation](https://ably.com/docs/guides/pub-sub/data-streaming.md#solution-message-conflation) delivers only the latest message per key in each time window. Use this for high-frequency updates where only the latest value matters.

### Use server-side batching

[Server-side batching](https://ably.com/docs/guides/pub-sub/data-streaming.md#solution-server-side-batching) groups messages into single deliveries. Use this for high-throughput channels where slight delay is acceptable.

### Enable delta compression

[Delta compression](https://ably.com/docs/channels/options/deltas.md) reduces payload size, lowering bandwidth costs. Use this for large, structurally similar successive messages.

### Use occupancy instead of presence

Use [occupancy](https://ably.com/docs/presence-occupancy/occupancy.md) instead of presence when you only need member counts, not individual identities. This avoids the n-squared presence event fan-out where each member event is delivered to every subscriber. For example, 200 members joining and leaving a channel generates approximately **80,400 messages**. See [large-scale presence sets](https://ably.com/docs/presence-occupancy/presence.md#large-presence) for the full calculation.

### Enable server-side presence batching

Enable [server-side batching](https://ably.com/docs/presence-occupancy/presence.md#large-presence) to group presence events and support up to 20,000 members per channel. Subscribe to presence updates only on channels where you need member-level detail.

## Documentation Index

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