GPT-5.6 Luna
$0.80
estimated usage cost
1,000 requests × (1,000 uncached input × $0.20 + 500 output × $1.20) / 1,000,000 = $0.80
base rates: up to 272,000 input tokens per request, inclusive.
Text generation / OpenAI
GPT-5.6 Luna
GPT-5.6 Luna is a text generation model from OpenAI, available through the Impossibl API. Its published context window is 1,050,000 tokens. The advertised input rate is $0.20 per million input tokens. The advertised output rate is $1.20 per million output tokens. Additional pricing brackets apply when the input exceeds a published context threshold.
api id: openai/gpt-5.6-luna
how much does gpt-5.6 luna cost?
published base api rates · usd per 1m tokens
- input
- $0.20
- output
- $1.20
- cache read
- $0.02
- cache write · default ttl
- $0.25
| total input | input | output | cache read | cache write |
|---|---|---|---|---|
| over 272,000 tokens | $0.40 | $1.80 | $0.04 | $0.50 |
crossing a threshold applies that bracket to the whole request. cache creation can have a separate charge.
rates are published by the impossibl api. balance-purchase fees, taxes, tool charges, and workspace-specific pricing are separate.
specifications & capabilities
- creator
- OpenAI
- model type
- Text generation
- context window
- 1.05m tokens
- maximum output
- not published in the catalog
- input types
- text, image
- output types
- text
- tool calling
- not verified in the catalog
unknown means the public catalog does not establish that fact. a model's documented capabilities can differ from what a particular api supports.
estimate your usage
estimate your api cost
estimate text token usage for your workload. all amounts are in usd.
estimates use published impossibl api usage rates. configured billing adjustments, funding fees, taxes, and custom workspace rates are excluded and may change the final amount.
image and audio usage, cache creation, and additional tool charges are excluded. reasoning tokens count as billable output, even when they are not visible in the response.
compare more Text generation models
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- GPT-3.5 Turbo$0.50 input / 1m tokenscompare →
independent benchmarks
Results from Artificial Analysis. Each configuration is listed separately. These evaluations describe the tested model configuration; performance and costs can differ on Impossibl. Last checked 2026-09-10.
GPT-5.6 Luna (max)
| Benchmark | Score |
|---|---|
| Intelligence Index | 37.50 |
| Omniscience Index | -10.28 |
| GPQA | 91.11% |
| Humanity’s Last Exam | 39.48% |
| SciCode | 53.59% |
| CritPt | 20.57% |
| Terminal-Bench v2.1 | 80.90% |
| Terminal-Bench v4.0 | 11.62% |
| AA-LCR | 83.67% |
| Multilingual LCR | 19.44% |
| Harvey LAB | 87.90% |
| GDPval Elo | 1489.33 |
| GDP.pdf All-pass | 24.00% |
| AutomationBench Partial | 50.21% |
| MMMU-Pro | 78.55% |
| Tau Banking | 31.13% |
| APEX-Agents | 35.84% |
| ITBench | 40.32% |
| coding index (API) | 71.4 |
| agentic index (API) | 42.7 |
| intelligence index (API) | 37.5 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗GPT-5.6 Luna (high)
| Benchmark | Score |
|---|---|
| Intelligence Index | 32.41 |
| Omniscience Index | -12.00 |
| GPQA | 89.19% |
| Humanity’s Last Exam | 33.41% |
| SciCode | 51.62% |
| CritPt | 16.57% |
| Terminal-Bench v2.1 | 69.66% |
| Terminal-Bench v4.0 | 2.53% |
| AA-LCR | 80.33% |
| Multilingual LCR | 12.22% |
| GDPval Elo | 1375.25 |
| GDP.pdf All-pass | 22.20% |
| AutomationBench Partial | 35.59% |
| MMMU-Pro | 77.57% |
| Tau Banking | 25.15% |
| coding index (API) | 63.3 |
| agentic index (API) | 35.6 |
| intelligence index (API) | 32.9 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗GPT-5.6 Luna (low)
| Benchmark | Score |
|---|---|
| Intelligence Index | 21.83 |
| Omniscience Index | -14.65 |
| GPQA | 83.54% |
| Humanity’s Last Exam | 19.83% |
| SciCode | 46.06% |
| CritPt | 2.57% |
| Terminal-Bench v2.1 | 43.45% |
| Terminal-Bench v4.0 | 0.00% |
| AA-LCR | 70.00% |
| Multilingual LCR | 6.11% |
| GDPval Elo | 1081.79 |
| AutomationBench Partial | 11.69% |
| MMMU-Pro | 73.99% |
| Tau Banking | 12.78% |
| coding index (API) | 44.2 |
| agentic index (API) | 17.9 |
| intelligence index (API) | 21.8 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗GPT-5.6 Luna (medium)
| Benchmark | Score |
|---|---|
| Intelligence Index | 25.78 |
| Omniscience Index | -13.18 |
| GPQA | 85.86% |
| Humanity’s Last Exam | 25.76% |
| SciCode | 46.76% |
| CritPt | 4.86% |
| Terminal-Bench v2.1 | 53.18% |
| Terminal-Bench v4.0 | 0.51% |
| AA-LCR | 75.00% |
| Multilingual LCR | 8.33% |
| GDPval Elo | 1196.42 |
| AutomationBench Partial | 23.07% |
| MMMU-Pro | 75.84% |
| Tau Banking | 17.73% |
| coding index (API) | 50.7 |
| agentic index (API) | 25.4 |
| intelligence index (API) | 25.8 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗GPT-5.6 Luna (Non-reasoning)
| Benchmark | Score |
|---|---|
| Intelligence Index | 16.76 |
| Omniscience Index | -24.95 |
| GPQA | 64.55% |
| Humanity’s Last Exam | 7.23% |
| CritPt | 0.29% |
| Terminal-Bench v2.1 | 38.95% |
| AA-LCR | 42.67% |
| GDPval Elo | 1007.01 |
| MMMU-Pro | 60.35% |
| Tau Banking | 9.69% |
| coding index (API) | 39.3 |
| agentic index (API) | 15.2 |
| intelligence index (API) | 16.8 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗GPT-5.6 Luna (xhigh)
| Benchmark | Score |
|---|---|
| Intelligence Index | 34.77 |
| Omniscience Index | -10.77 |
| GPQA | 89.49% |
| Humanity’s Last Exam | 36.98% |
| SciCode | 50.46% |
| CritPt | 20.57% |
| Terminal-Bench v2.1 | 77.90% |
| Terminal-Bench v4.0 | 3.54% |
| AA-LCR | 81.67% |
| Multilingual LCR | 16.11% |
| GDPval Elo | 1428.47 |
| GDP.pdf All-pass | 23.80% |
| AutomationBench Partial | 42.60% |
| MMMU-Pro | 78.55% |
| Tau Banking | 28.66% |
| coding index (API) | 68.6 |
| agentic index (API) | 39.5 |
| intelligence index (API) | 34.8 |
Unmeasured scores are omitted. API values retain their source units.
view source ↗frequently asked questions
What is GPT-5.6 Luna?
GPT-5.6 Luna is a text-generation model from OpenAI, available through the Impossibl API.
How much does GPT-5.6 Luna cost?
GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens through the Impossibl API. Cache reads cost $0.02 per million tokens; cache writes cost $0.25 per million tokens. These base rates apply through 272,000 total input tokens per request. Above 272,000 input tokens, the long-context rates in the pricing table apply to the whole request. All rates are in USD.
What is the context length of GPT-5.6 Luna?
GPT-5.6 Luna has a 1,050,000-token context window through the Impossibl API.
What inputs and outputs does GPT-5.6 Luna support?
GPT-5.6 Luna accepts text and image as input. GPT-5.6 Luna returns text.
How do I use GPT-5.6 Luna through an API?
GPT-5.6 Luna is available through the Impossibl API. Use openai/gpt-5.6-luna as the model identifier with /v1/chat/completions. The quickstart explains how to create an API key and send your first request.
When was GPT-5.6 Luna released?
OpenAI released GPT-5.6 Luna on July 9, 2026.
sources & coverage
this page describes GPT-5.6 Luna as listed by the impossibl public api. prices and availability come from that catalog, refreshed here every five minutes. this is an impossibl offering, not a comparison of independent hosting-provider quotes.
model descriptions and release dates, where available, use the creator sources linked in the faq. api prices and limits use the impossibl catalog. benchmark results, where available, are credited to Artificial Analysis in the benchmarks section. report a correction →