# C04 — Prompt caching

- Publisher: OpenAI
- Source: [Prompt caching](https://developers.openai.com/api/docs/guides/prompt-caching)
- Published: Not stated / not established
- Updated: Not stated / not established
- Accessed: 2026-10-22
- Type: Official implementation documentation
- Evidence: opened primary page; relevant content read.

## Paraphrased finding

Caching reuses an unchanged prefix. GPT-5.6+ has a 1,024-visible-token minimum and separately priced writes. Verify actual read/write counters.

## Limits

Requires reuse while cache is valid; cache read discount is not a whole-application saving; model and retention settings differ.