---
title: "How do I verify OpenAI prompt caching is lowering API costs?"  
description: "How do I verify OpenAI prompt caching is lowering API costs?"  
author: "Dmitry Belov"  
published: 2026-10-16  
updated: 2026-10-16  
canonical: https://www.mindstick.com/forum/162455/how-do-i-verify-openai-prompt-caching-is-lowering-api-costs  
category: "OpenAI API"  
tags: ["OpenAI", "api(s)", "Prompt Caching"]  
reading_time: 1 minute  

---

# How do I verify OpenAI prompt caching is lowering API costs?

I’m trying to work out whether prompt caching is making a meaningful difference to my API spend, rather than just assuming it is because my requests share a long system prompt.

When comparing usage across calls, which **cached token usage** fields or billing details should I look at? I’m also curious how much the prefix needs to match for caching to help in a real application.


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Original Source: https://www.mindstick.com/forum/162455/how-do-i-verify-openai-prompt-caching-is-lowering-api-costs

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