GPT-5.6 Luna API Pricing: Cost Calculator & Real Examples (2026)
GPT-5.6 Luna charges $0.20 per 1 million input tokens and $1.20 per 1 million output tokens. But per-token prices don't answer the real question: what will your workload cost per month? Below we compute it for three realistic scenarios — or run your own numbers with GPT-5.6 Luna preselected.
| Meter | Price per 1M tokens |
|---|---|
| Input | $0.20 |
| Cached input | $0.02 |
| Output | $1.20 |
Note: Standard short-context pricing. Long-context and Fast mode requests use different rates.
What does GPT-5.6 Luna cost in practice?
| Monthly scenario | Token bill |
|---|---|
| Support chatbot (150k requests, 400 in / 300 out tokens) | $66.00 |
| Document workflow (22k runs, 3,000 in / 400 out tokens) | $23.76 |
| High-volume classifier (1M requests, 300 in / 10 out tokens) | $72.00 |
In the chatbot scenario, output is ~82% of the GPT-5.6 Luna bill — capping response length (max tokens) is the most direct optimization. Document workflows are input-heavy, so the input rate dominates there.
Prompt caching savings
GPT-5.6 Luna offers cached input at $0.02/1M (vs $0.20 standard). At a 60% cache-hit rate, the example chatbot drops from $66.00 to $59.52/month — saving $6.48. If your system prompt and context are stable, this discount is free money.
Is GPT-5.6 Luna cheap or expensive?
On the same chatbot workload, GPT-5.6 Luna is cheaper than 9 of the 11 models we track (position 3 of 12, cheapest to priciest). The nearest cheaper alternative is Mistral Small 4 ($36.00/month on the same scenario). One step up: Gemini 2.5 Flash ($130.50/month). The right decision isn't absolute price but the cheapest model that meets your quality bar — test before overpaying.
FAQ
How much does GPT-5.6 Luna cost per 1M tokens?
$0.20 per 1M input tokens and $1.20 per 1M output tokens (verified 2026-09-17).
What does a chatbot cost on GPT-5.6 Luna?
A 500-active-user chatbot (10 questions/day, 400 input + 300 output tokens per request) costs ~$66.00/month in tokens on GPT-5.6 Luna. Adjust the assumptions in the calculator.
Our take on this model
Luna is the small, fast tier of GPT-5.6. At $0.20 input and $1.20 output per million tokens for standard short-context requests, it is built for high-volume classification, routing, extraction and short support answers.
Its cache-read rate is $0.02 per million tokens. Stable prompts can therefore reduce the input portion sharply, but output length still deserves a hard cap because generated tokens remain six times the uncached input rate.
Prices verified on 2026-09-17 against the provider's official pricing page. Estimates are for planning purposes only — always confirm current pricing with the provider.