Back to Text & reasoning
Model comparison
GPT-6 Luna vs GPT-5.6 Terra
Compare GPT-6 Luna and GPT-5.6 Terra using the same provider-sourced text & reasoning rubric. No mystery score and no invented benchmark ranking.
Estimate your cost
Set your usage. Your estimate updates as you type.
Example: 6,000 input tokens for 10 pages, plus a 500-token summary. Page lengths vary; adjust the numbers below.
One run sends your input to the model once and receives an answer. Tokens are pieces of text: input is what you send, output is the answer you receive.
Advanced options
How this estimate works
Estimates exclude taxes, tools, cache storage/writes, free allowances and custom discounts. Image estimates cover output only, not prompt or reference-image charges. Quality modes differ by model. Unlisted settings are not treated as free.
| Model | Access | Estimated total (USD) |
|---|---|---|
| GPT-6 LunaOpenAI | OpenAI | $0.0009 |
| GPT-5.6 TerraOpenAI | OpenAI | $0.018 |
Quick take
GPT-6 Luna
A low-cost OpenAI model for focused tasks repeated at scale, such as extraction, classification and short replies.
Best for
- Data extraction
- Request routing
- High-volume customer replies
Watch out for
Use Responses for tools with reasoning. Chat Completions function calling requires reasoning_effort=none. Fine-tuning is not supported, and long prompts trigger higher prices.
GPT-5.6 Terra
A lower-cost GPT-5.6 option for coding, analysis and assistants that use tools.
Best for
- Coding assistants
- Everyday analysis
Watch out for
Long context, reasoning and tool calls can cost more than the headline token rate.
Compare the published facts
GPT-6 Luna vs GPT-5.6 Terra
Values use each provider's own published units and limits. A blank means the provider did not publish a directly comparable value in the sources reviewed.
| Text & reasoning | GPT-6 Luna | GPT-5.6 Terra |
|---|---|---|
| Context windowMaximum combined prompt and working context documented by the provider. | 1.05M tokens | 1.05M tokens |
| Maximum outputProvider-published response limit, where available. | 128K tokens | 128K tokens |
| Knowledge cutoffLatest reliable knowledge date explicitly published by the model provider. Search and connected tools can retrieve newer information but do not change the model's built-in cutoff. | May 18, 2026 | February 16, 2026 |
| Input priceCurrent standard list price per million input tokens unless noted. | $0.10 / 1M | $2 / 1M |
| Output priceCurrent standard list price per million output tokens unless noted. | $0.50 / 1M | $12 / 1M |
| InputsMedia types accepted by the listed model endpoint. | Text, image | Text, image |
| Tools & agentsSelected native tools and agent-building capabilities, not an exhaustive list. | Functions, web/file search, code, computer, MCP | Functions, web/file search, code, computer, MCP |
How to choose
Compare the job, not the hype.
Start with the job you need to complete, then validate cost, access, and policy details on your exact provider route.
GPT-6 Luna
OpenAI says API inputs and outputs are not used for model training by default. Default abuse-monitoring logs may be retained for up to 30 days; qualifying organizations can request other controls.
Provider and API links
GPT-5.6 Terra
OpenAI says API inputs and outputs are not used for model training by default. Default abuse-monitoring logs may be retained for up to 30 days; qualifying organizations can request other controls.
Provider and API links
Frequently asked questions
GPT-6 Luna vs GPT-5.6 Terra FAQ
What is the main difference between GPT-6 Luna and GPT-5.6 Terra?
GPT-6 Luna: A low-cost OpenAI model for focused tasks repeated at scale, such as extraction, classification and short replies. GPT-5.6 Terra: A lower-cost GPT-5.6 option for coding, analysis and assistants that use tools.
Should I choose GPT-6 Luna or GPT-5.6 Terra?
Consider GPT-6 Luna when your priority is Data extraction. Consider GPT-5.6 Terra when your priority is Coding assistants. Test both with your own data and provider route before committing.
Is this GPT-6 Luna vs GPT-5.6 Terra comparison based on Cody benchmarks?
No. This comparison aligns provider-published facts for the Text & reasoning category. It does not claim a universal winner or combine incompatible third-party benchmark scores.