MoonshotAI: Kimi K3 vs OpenAI: GPT-5.6 Luna
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-09-27.
| MoonshotAI: Kimi K3 | OpenAI: GPT-5.6 Luna | |
|---|---|---|
| Vendor | moonshotai | openai |
| Quality Score | 100 | 100 |
| Benchmark Score | 73.9 | 62.3 |
| Input Price | $3.00/M | $0.20/M |
| Output Price | $15.00/M | $1.20/M |
| Context Window | 1,048,576 | 1,050,000 |
| Max Output | 943,718 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 71.9 | 61.6 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-5.6 Luna costs $0.50 and Kimi K3 costs $6.75, so GPT-5.6 Luna is about 13.5 times cheaper for the same work.
Both take in a similar amount of text: 1,048,576 and 1,050,000 tokens, about 1,573 and 1,575 pages.
Only Kimi K3 offers video input.
On our blended benchmark score Kimi K3 leads 73.9 to 62.3.
Across the 19 tasks where they differ, Kimi K3 scores higher on 10 (Code Review, Code Refactoring, Bug Fixing and others), GPT-5.6 Luna on 9 (SQL Generation, Code Completion, Code Documentation and others).
Pick Kimi K3 if you need video input or benchmark performance; pick GPT-5.6 Luna if you need lower cost.
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 | MoonshotAI: Kimi K3 | OpenAI: GPT-5.6 Luna |
|---|---|---|
| SQL Generation | 140 | 141 |
| Code Review | 145 | 143 |
| Code Completion | 117 | 133 |
| Code Refactoring | 147 | 145 |
| Bug Fixing | 149 | 147 |
| Unit Test Generation | 132 | 131 |
| Code Documentation | 134 | 137 |
| Regex Writing | 123 | 125 |
| CI/CD Pipelines | 128 | 127 |
| Frontend Component Design | 130 | 129 |
| Data Analysis | 134 | 133 |
| CSV / Spreadsheet Cleanup | 135 | 136 |
| ETL Scripting | 138 | 136 |
| JSON Extraction | 120 | 131 |
| Bulk Data Labeling | 116 | 129 |
| OCR / Document Parsing | 134 | 134 |
| Table Extraction from PDFs | 134 | 134 |
| Short-Form Summarization | 116 | 126 |
| Blog Post Writing | 128 | 129 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →