Prices → Compare → GPT-5.6 Sol vs GPT-5.6 Luna
GPT-5.6 Sol vs GPT-5.6 Luna: API cost compared
GPT-5.6 Sol lists at $2.500 in / $15.00 out per 1M tokens. GPT-5.6 Luna lists at $0.100 in / $0.600. Sticker price only tells you so much — below is what each actually costs across eight production workloads.
Side by side
| GPT-5.6 Sol | GPT-5.6 Luna | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input per 1M | $2.500 | $0.100 |
| Output per 1M | $15.00 | $0.600 |
| Cached input per 1M | $0.250 | $0.010 |
| Context window | 400k | 400k |
| Blended per 1M (3:1) | $5.625 | $0.225 |
Monthly cost by workload
Caching applied at each workload's typical hit rate. This is where the two models actually separate.
| Workload | GPT-5.6 Sol | GPT-5.6 Luna | Cheaper | Difference |
|---|---|---|---|---|
| Customer support chatbot | $366.00 | $14.64 | GPT-5.6 Luna | $351.36 (96%) |
| RAG document Q&A | $490.00 | $19.60 | GPT-5.6 Luna | $470.40 (96%) |
| Coding agent | $261.25 | $10.45 | GPT-5.6 Luna | $250.80 (96%) |
| Bulk summarization | $3,465 | $138.60 | GPT-5.6 Luna | $3,326 (96%) |
| Structured data extraction | $4,675 | $187.00 | GPT-5.6 Luna | $4,488 (96%) |
| Long-form content generation | $636.50 | $25.46 | GPT-5.6 Luna | $611.04 (96%) |
| Email triage agent | $1,081 | $43.25 | GPT-5.6 Luna | $1,038 (96%) |
| Translation pipeline | $4,112 | $164.47 | GPT-5.6 Luna | $3,947 (96%) |
How to read this
GPT-5.6 Luna is cheaper on the majority of these workloads, but "majority" is not the decision. The output:input price ratio is 6.0 for GPT-5.6 Sol and 6.0 for GPT-5.6 Luna. If your traffic is output-heavy — long-form drafting, translation — the model with the lower output price wins regardless of what the input price suggests. If you are input-heavy — RAG, bulk summarization, agents re-reading a codebase — the cached input rate matters more than either headline number.
Cost is also not the only axis. This site does not benchmark quality, latency, or rate limits, and a model that is 3x cheaper but needs two attempts per task is not cheaper. Use these numbers to size a bill, then validate on your own evals.
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| Model | In /1M | Out /1M | Monthly | vs best |
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