OpenAI: GPT-5.6 Luna vs xAI: Grok Latest
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-10-09.
| OpenAI: GPT-5.6 Luna | xAI: Grok Latest | |
|---|---|---|
| Vendor | openai | ~x-ai |
| Quality Score | 100 | 100 |
| Benchmark Score | 62.3 | 5.8 |
| Input Price | $0.20/M | $2.00/M |
| Output Price | $1.20/M | $6.00/M |
| Context Window | 1,050,000 | 500,000 |
| Max Output | 128,000 | 450,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 61.6 | 11.4 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-5.6 Luna costs $0.50 and Grok Latest costs $3.50, so GPT-5.6 Luna is about 7.0 times cheaper for the same work.
GPT-5.6 Luna reads up to 1,050,000 tokens at once, roughly 1,575 pages of text, against about 750 pages for Grok Latest.
On our blended benchmark score GPT-5.6 Luna leads 62.3 to 5.8.
Across the 20 tasks where they differ, GPT-5.6 Luna scores higher on 20 (SQL Generation, Code Review, Code Completion and others).
Pick GPT-5.6 Luna if you need lower cost, long documents, benchmark performance or the stronger all-round task scores.
Costs use current list prices per million tokens; page counts assume about 0.75 words per token and 500 words per page.
Who wins by task?
| Task | OpenAI: GPT-5.6 Luna | xAI: Grok Latest |
|---|---|---|
| SQL Generation | 141 | 134 |
| Code Review | 143 | 134 |
| Code Completion | 133 | 118 |
| Code Refactoring | 145 | 137 |
| Bug Fixing | 147 | 138 |
| Unit Test Generation | 131 | 125 |
| Code Documentation | 137 | 131 |
| Regex Writing | 125 | 119 |
| CI/CD Pipelines | 127 | 121 |
| Frontend Component Design | 129 | 123 |
| Data Analysis | 133 | 125 |
| CSV / Spreadsheet Cleanup | 136 | 133 |
| ETL Scripting | 136 | 129 |
| JSON Extraction | 131 | 122 |
| Bulk Data Labeling | 129 | 119 |
| OCR / Document Parsing | 134 | 131 |
| Table Extraction from PDFs | 134 | 131 |
| Long-Document Summarization | 147 | 139 |
| Short-Form Summarization | 126 | 115 |
| Blog Post Writing | 129 | 122 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →