GPT-5.4 vs GPT-6 Luna
GPT-6 Luna is 28.1× cheaper for typical traffic ; GPT-5.4 scores higher on the Artificial Analysis intelligence index (39 vs 38.1).
Prices checked Oct 21, 2026
| GPT-5.4 | GPT-6 Luna | |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Input / 1M tokens | $2.50 | $0.10 |
| Output / 1M tokens | $15.00 | $0.50 |
| Cached input / 1M | $0.25 | $0.01 |
| Context window | 1.05M | 1.05M |
| Max output | 128K | 128K |
| Intelligence index | 39 | 38.1 |
| Image input | Yes | Yes |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
| Open weights | No | No |
Monthly cost for common workloads
| Workload | GPT-5.4 | GPT-6 Luna |
|---|---|---|
| Customer chatbot 1,000 conversations a day, 8 turns each | $1,674 | $58.56 |
| Document Q&A (RAG) 500 questions a day over retrieved documents | $317 | $11.94 |
| Coding / tool-using agent 200 tasks a day, long tool-heavy contexts | $653 | $23.70 |
| Content generation 30 long articles a day | $40.50 | $1.40 |
| Classification / extraction 100,000 short items a day | $2,925 | $112 |
Estimates include cached-input discounts where a model offers them. Try your own numbers in the cost calculator.
Which one to choose
- Lowest cost: GPT-6 Luna — 28.1× cheaper on a 3:1 input/output mix.