SpaceXAI: Grok 4.6 vs OpenAI: GPT-5.6 Terra
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-09-27.
| SpaceXAI: Grok 4.6 | OpenAI: GPT-5.6 Terra | |
|---|---|---|
| Vendor | x-ai | openai |
| Quality Score | 100 | 100 |
| Benchmark Score | 75.3 | 71.1 |
| Input Price | $2.00/M | $2.00/M |
| Output Price | $6.00/M | $12.00/M |
| Context Window | 500,000 | 1,050,000 |
| Max Output | 450,000 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 73.1 | 69.4 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Grok 4.6 costs $3.50 and GPT-5.6 Terra costs $5.00, so Grok 4.6 is about 1.4 times cheaper for the same work.
GPT-5.6 Terra reads up to 1,050,000 tokens at once, roughly 1,575 pages of text, against about 750 pages for Grok 4.6.
On our blended benchmark score Grok 4.6 leads 75.3 to 71.1.
Across the 20 tasks where they differ, Grok 4.6 scores higher on 20 (SQL Generation, Code Review, Code Completion and others).
Grok 4.6 was released in August 2026 and GPT-5.6 Terra in July 2026.
Pick Grok 4.6 if you need lower cost, benchmark performance or the stronger all-round task scores; pick GPT-5.6 Terra if you need long documents.
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 | SpaceXAI: Grok 4.6 | OpenAI: GPT-5.6 Terra |
|---|---|---|
| SQL Generation | 142 | 140 |
| Code Review | 145 | 145 |
| Code Completion | 119 | 118 |
| Code Refactoring | 147 | 147 |
| Bug Fixing | 149 | 149 |
| Unit Test Generation | 132 | 132 |
| Code Documentation | 137 | 135 |
| Regex Writing | 125 | 124 |
| CI/CD Pipelines | 128 | 128 |
| Frontend Component Design | 130 | 130 |
| Data Analysis | 135 | 134 |
| CSV / Spreadsheet Cleanup | 136 | 135 |
| ETL Scripting | 138 | 137 |
| JSON Extraction | 122 | 121 |
| Bulk Data Labeling | 119 | 117 |
| OCR / Document Parsing | 134 | 134 |
| Table Extraction from PDFs | 134 | 134 |
| Long-Document Summarization | 148 | 147 |
| Short-Form Summarization | 118 | 116 |
| Blog Post Writing | 130 | 128 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →