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October 1, 2024

Prompt Caching in the API

Offering automatic discounts on inputs that the model has recently seen

DALL·E generated impressionist oil painting of layered light green columns interwoven with parallel emerald streams, forming a harmonious and repetitive tapestry.

Many developers use the same context repeatedly across multiple API calls when building AI applications, like when making edits to a codebase or having long, multi-turn conversations with a chatbot. Today, we’re introducing Prompt Caching, allowing developers to reduce costs and latency. By reusing recently seen input tokens, developers can get a 50% discount and faster prompt processing times.

Prompt Caching Availability & Pricing

Starting today, Prompt Caching is automatically applied on the latest versions of GPT-4o, GPT-4o mini, o1-preview and o1-mini, as well as fine-tuned versions of those models. Cached prompts are offered at a discount compared to uncached prompts.

Here's an overview of pricing:

Uncached Input Tokens

Cached Input Tokens

Output Tokens

GPT-4o

gpt-4o-2024-08-06

$2.50

$1.25

$10.00

GPT-4o fine-tuning

$3.75

$1.875

$15.00

GPT-4o mini

gpt-4o-mini-2024-07-18

$0.15

$0.075

$0.60

GPT-4o mini fine-tuning

$0.30

$0.15

$1.20

o1

o1-preview

$15.00

$7.50

$60.00

o1 mini

$3.00

$1.50

$12.00

Monitoring Cache Usage

API calls to supported models will automatically benefit from Prompt Caching on prompts longer than 1,024 tokens. The API caches the longest prefix of a prompt that has been previously computed, starting at 1,024 tokens and increasing in 128-token increments. If you reuse prompts with common prefixes, we will automatically apply the Prompt Caching discount without requiring you to make any changes to your API integration.

Requests using Prompt Caching have a cached_tokens value within the usage field in the API response:

javascript
1
usage: {
2
  total_tokens: 2306,
3
  prompt_tokens: 2006,
4
  completion_tokens: 300,
5
  
6
  prompt_tokens_details: {
7
    cached_tokens: 1920,
8
    audio_tokens: 0,
9
  },
10
  completion_tokens_details: {
11
    reasoning_tokens: 0,
12
    audio_tokens: 0,
13
  }
14
}

Caches are typically cleared after 5-10 minutes of inactivity and are always removed within one hour of the cache's last use. As with all API services, Prompt Caching is subject to our Enterprise privacy commitments. Prompt caches are not shared between organizations.

Prompt Caching is one of a variety of tools for developers to scale their applications in production while balancing performance, cost and latency. For more information, check out the Prompt Caching docs(opens in a new window).

Author

OpenAI