# Source: https://platform.claude.com/docs/en/api/service-tiers.md

# Service tiers

Different tiers of service allow you to balance availability, performance, and predictable costs based on your application's needs.

---

We offer three service tiers:
- **Priority Tier:** Best for workflows deployed in production where time, availability, and predictable pricing are important
- **Standard:** Default tier for both piloting and scaling everyday use cases
- **Batch:** Best for asynchronous workflows which can wait or benefit from being outside your normal capacity

## Standard Tier

The standard tier is the default service tier for all API requests. Requests in this tier are prioritized alongside all other requests and observe best-effort availability.

## Priority Tier

Requests in this tier are prioritized over all other requests to Anthropic. This prioritization helps minimize ["server overloaded" errors](/docs/en/api/errors#http-errors), even during peak times.

For more information, see [Get started with Priority Tier](#get-started-with-priority-tier)

## How requests get assigned tiers

When handling a request, Anthropic decides to assign a request to Priority Tier in the following scenarios:
- Your organization has sufficient priority tier capacity **input** tokens per minute
- Your organization has sufficient priority tier capacity **output** tokens per minute

Anthropic counts usage against Priority Tier capacity as follows:

**Input Tokens**
- Cache reads as 0.1 tokens per token read from the cache
- Cache writes as 1.25 tokens per token written to the cache with a 5 minute TTL
- Cache writes as 2.00 tokens per token written to the cache with a 1 hour TTL
- For [long-context](/docs/en/build-with-claude/context-windows) (>200k input tokens) requests, input tokens are 2 tokens per token
- All other input tokens are 1 token per token

**Output Tokens**
- For [long-context](/docs/en/build-with-claude/context-windows) (>200k input tokens) requests, output tokens are 1.5 tokens per token
- All other output tokens are 1 token per token

Otherwise, requests proceed at standard tier.

<Note>
Requests assigned Priority Tier pull from both the Priority Tier capacity and the regular rate limits.
If servicing the request would exceed the rate limits, the request is declined.
</Note>

## Using service tiers

You can control which service tiers can be used for a request by setting the `service_tier` parameter:

```python
message = client.messages.create(
    model="claude-sonnet-4-5",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello, Claude!"}],
    service_tier="auto"  # Automatically use Priority Tier when available, fallback to standard
)
```

The `service_tier` parameter accepts the following values:

- `"auto"` (default) - Uses the Priority Tier capacity if available, falling back to your other capacity if not
- `"standard_only"` - Only use standard tier capacity, useful if you don't want to use your Priority Tier capacity

The response `usage` object also includes the service tier assigned to the request:

```json
{
  "usage": {
    "input_tokens": 410,
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "output_tokens": 585,
    "service_tier": "priority"
  }
}
```
This allows you to determine which service tier was assigned to the request.

When requesting `service_tier="auto"` with a model with a Priority Tier commitment, these response headers provide insights:
```
anthropic-priority-input-tokens-limit: 10000
anthropic-priority-input-tokens-remaining: 9618
anthropic-priority-input-tokens-reset: 2025-01-12T23:11:59Z
anthropic-priority-output-tokens-limit: 10000
anthropic-priority-output-tokens-remaining: 6000
anthropic-priority-output-tokens-reset: 2025-01-12T23:12:21Z
```
You can use the presence of these headers to detect if your request was eligible for Priority Tier, even if it was over the limit.

## Get started with Priority Tier

You may want to commit to Priority Tier capacity if you are interested in:
- **Higher availability**: Target 99.5% uptime with prioritized computational resources
- **Cost Control**: Predictable spend and discounts for longer commitments
- **Flexible overflow**: Automatically falls back to standard tier when you exceed your committed capacity

Committing to Priority Tier will involve deciding:
- A number of input tokens per minute
- A number of output tokens per minute
- A commitment duration (1, 3, 6, or 12 months)
- A specific model version

<Note>
The ratio of input to output tokens you purchase matters. Sizing your Priority Tier capacity to align with your actual traffic patterns helps you maximize utilization of your purchased tokens.
</Note>

### Supported models

Priority Tier is supported by:

- Claude Opus 4.5
- Claude Sonnet 4.5
- Claude Haiku 4.5
- Claude Opus 4.1
- Claude Opus 4
- Claude Sonnet 4
- Claude Sonnet 3.7 ([deprecated](/docs/en/about-claude/model-deprecations))
- Claude Haiku 3.5 ([deprecated](/docs/en/about-claude/model-deprecations))

Check the [model overview page](/docs/en/about-claude/models/overview) for more details on our models.

### How to access Priority Tier

To begin using Priority Tier:

1. [Contact sales](https://claude.com/contact-sales/priority-tier) to complete provisioning
2. (Optional) Update your API requests to optionally set the `service_tier` parameter to `auto`
3. Monitor your usage through response headers and the Claude Console