High-volume, cost-sensitive work
Choose GPT-5 nano
GPT-5 nano costs 31% less on a typical mix of three input tokens for every output token ($0.14 against $0.20 per million tokens).
GPT-5 nano vs GPT-6 Luna Pro: price, context and capabilities
Choose GPT-5 nano for high-volume, cost-sensitive work, writing and code generation and reused prompts and documents (RAG, agents). Choose GPT-6 Luna Pro for very long inputs and the latest release.
In short
- GPT-5 nano is 31% cheaper than GPT-6 Luna Pro at the headline price ($0.1375 / 1M tokens vs $0.20 / 1M tokens).
- GPT-6 Luna Pro reads more per request: 1.05M tokens against 400k.
- GPT-6 Luna Pro is the newer model (Sep 22, 2026, against Aug 7, 2025).
- Only GPT-5 nano offers batch api.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose GPT-5 nano
GPT-5 nano charges $0.40 per million output tokens, against $0.50 for GPT-6 Luna Pro. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose GPT-5 nano
GPT-5 nano charges <$0.01 per million cached input tokens, against $0.01 for GPT-6 Luna Pro.
Very long inputs
Choose GPT-6 Luna Pro
GPT-6 Luna Pro reads up to 1.05M tokens per request, against 400k for GPT-5 nano.
Latest release
Choose GPT-6 Luna Pro
GPT-6 Luna Pro is the newer release (Sep 22, 2026, against Aug 7, 2025 for GPT-5 nano).
Monthly cost at three volumes
| Volume | GPT-5 nano | GPT-6 Luna Pro | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $0.15 | $0.23 | GPT-5 nano, $0.08 less |
| Production: 20M input, 5M output tokens | $3.00 | $4.50 | GPT-5 nano, $1.50 less |
| Scale: 500M input, 100M output tokens | $65.00 | $100.00 | GPT-5 nano, $35.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| GPT-5 nano | GPT-6 Luna Pro | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Category | Language models | Language models |
| Status | Legacy | Generally available |
| Headline price | $0.1375 / 1M tokens | $0.20 / 1M tokens |
| Input | $0.05 / 1M tokens | $0.10 / 1M tokens |
| Output | $0.40 / 1M tokens | $0.50 / 1M tokens |
| Cached input | $0.005 / 1M tokens | $0.01 / 1M tokens |
| Context window | 400k | 1.05M |
| Max output | 128k | 128k |
| Released | Aug 7, 2025 | Sep 22, 2026 |
| Knowledge cutoff | May 2024 | No data |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching |
| API model id | gpt-5-nano | gpt-6-luna-pro |
Benchmarks side by side
Leader in bold.
| Benchmark | GPT-5 nano | GPT-6 Luna Pro |
|---|---|---|
| Terminal-Bench Hard | 12.1% | No data |
| GPQA Diamond | 67.6% | No data |
| Humanity's Last Exam | 9.5% | No data |
| IFBench (instruction following) | 67.6% | No data |
| τ²-Bench (agentic tool use) | 36.5% | No data |
| MMMU-Pro (visual reasoning) | 61% | No data |
| Long-context reasoning (AA-LCR) | 45% | No data |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose GPT-5 nano or GPT-6 Luna Pro?
Choose GPT-5 nano for high-volume, cost-sensitive work, writing and code generation and reused prompts and documents (RAG, agents). Choose GPT-6 Luna Pro for very long inputs and the latest release.
Which is cheaper, GPT-5 nano or GPT-6 Luna Pro?
GPT-5 nano is 31% cheaper than GPT-6 Luna Pro at the headline price ($0.1375 / 1M tokens vs $0.20 / 1M tokens).
Which has the larger context window, GPT-5 nano or GPT-6 Luna Pro?
GPT-6 Luna Pro reads more per request: 1.05M tokens against 400k.
What is the difference between GPT-5 nano and GPT-6 Luna Pro?
GPT-5 nano is made by OpenAI and GPT-6 Luna Pro by OpenAI. GPT-5 nano is 31% cheaper than GPT-6 Luna Pro at the headline price ($0.1375 / 1M tokens vs $0.20 / 1M tokens). GPT-6 Luna Pro reads more per request: 1.05M tokens against 400k. GPT-6 Luna Pro is the newer model (Sep 22, 2026, against Aug 7, 2025). Only GPT-5 nano offers batch api.
How much do GPT-5 nano and GPT-6 Luna Pro cost per month?
At 20 million input and 5 million output tokens a month, GPT-5 nano costs $3.00 and GPT-6 Luna Pro costs $4.50, at standard rates.
Which is newer, GPT-5 nano or GPT-6 Luna Pro?
GPT-6 Luna Pro was released on Sep 22, 2026 and GPT-5 nano on Aug 7, 2025.