GPT-5.5 vs GPT-5.4: which API costs less?
Averaged across three realistic workloads, GPT-5.4 is about 50% cheaper than GPT-5.5. Below: raw rates and side-by-side monthly costs, computed from prices verified 2026-10-17 (we track what you are billed today, promos included).
Rates per 1M tokens
GPT-5.5: Prompts up to 272K tokens; longer prompts cost more. GPT-5.4: Prompts up to 272K tokens; longer prompts cost more.
Monthly cost, side by side
| Workload | GPT-5.5 | GPT-5.4 | Difference |
|---|---|---|---|
Customer-support chatbot 2M input + 0.5M output tokens/month, 60% of input served from prompt cache | $19.60 | $9.80 | GPT-5.4 −50% |
RAG / document Q&A 20M input + 1M output tokens/month, 70% cached (shared context) | $67.00 | $33.50 | GPT-5.4 −50% |
Agentic coding assistant 50M input + 5M output tokens/month, 80% cached (long sessions) | $220 | $110 | GPT-5.4 −50% |
Your traffic looks different? Run your own numbers in the calculator.
FAQ
Which is cheaper: GPT-5.5 or GPT-5.4?
Across three realistic workloads (chatbot, RAG, agent), GPT-5.4 works out about 50% cheaper than GPT-5.5 on average. Raw rates: GPT-5.5 $5/$30 per 1M tokens vs GPT-5.4 $2.50/$15. Verified 2026-10-17.
Does prompt caching change the comparison?
Yes — cached input costs $0.500 on GPT-5.5 and $0.250 on GPT-5.4. Our scenario numbers already include realistic cache hit rates.
Is cheaper always better?
No. Price is one axis — model capability, context window and latency differ. This page answers only the cost question; benchmark quality on your own tasks before switching.