Should I use prompt caching to reduce token spend?

Yes—if your prompts are large and repeated, prompt caching can materially reduce token spend.

Good reasons to use it

• Repeated system / developer instructions: If you send the same long instructions every request, caching can save a lot.
• RAG or tool-heavy apps: If you prepend a stable context block, caching helps.
• Long conversations with shared prefixes: Reusing the same initial context makes caching valuable.
• High-volume workloads: Savings add up quickly.

When it’s not worth it

• Short prompts: Savings are usually small.
• Highly variable prompts: If the prefix changes a lot, cache hits will be low.
• Low traffic: The engineering complexity may not be worth it.

Important caveats

• Caching typically helps only on the reused prefix, not the changing user-specific tail.
• You’ll want to structure prompts so the static part comes first and stays byte-for-byte consistent.
• Measure real usage: sometimes the operational effort exceeds the savings.

Rule of thumb

If you have:

• a large static prefix,
• frequent repeated calls, and
• meaningful token spend,

then yes, use prompt caching.

If you want, I can help you estimate the savings for your specific prompt pattern.