MoonshotAI: Kimi K2.6 vs OpenAI: GPT-5.3-Codex
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| MoonshotAI: Kimi K2.6 | OpenAI: GPT-5.3-Codex | |
|---|---|---|
| Vendor | moonshotai | openai |
| Quality Score | 100 | 100 |
| Benchmark Score | 76.7 | 73.4 |
| Input Price | $0.65/M | $1.75/M |
| Output Price | $3.41/M | $14.00/M |
| Context Window | 262,144 | 400,000 |
| Max Output | 235,929 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 73.0 | 73.0 |
| ai_index_agentic | 49.9 | - |
| ai_index_coding | 100.0 | - |
| eqbench | 63.5 | - |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Kimi K2.6 costs $1.50 and GPT-5.3-Codex costs $5.25, so Kimi K2.6 is about 3.5 times cheaper for the same work.
GPT-5.3-Codex reads up to 400,000 tokens at once, roughly 600 pages of text, against about 393 pages for Kimi K2.6.
On our blended benchmark score Kimi K2.6 leads 76.7 to 73.4.
Across the 20 tasks where they differ, Kimi K2.6 scores higher on 20 (SQL Generation, Code Review, Code Completion and others).
Kimi K2.6 was released in April 2026 and GPT-5.3-Codex in February 2026.
Pick Kimi K2.6 if you need lower cost, benchmark performance or the stronger all-round task scores; pick GPT-5.3-Codex 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 | MoonshotAI: Kimi K2.6 | OpenAI: GPT-5.3-Codex |
|---|---|---|
| SQL Generation | 168 | 141 |
| Code Review | 164 | 145 |
| Code Completion | 131 | 118 |
| Code Refactoring | 160 | 147 |
| Bug Fixing | 174 | 149 |
| Unit Test Generation | 152 | 132 |
| Code Documentation | 140 | 135 |
| Regex Writing | 136 | 124 |
| CI/CD Pipelines | 142 | 128 |
| Frontend Component Design | 145 | 130 |
| Data Analysis | 166 | 134 |
| CSV / Spreadsheet Cleanup | 151 | 135 |
| ETL Scripting | 151 | 138 |
| JSON Extraction | 147 | 120 |
| Bulk Data Labeling | 134 | 117 |
| OCR / Document Parsing | 144 | 134 |
| Table Extraction from PDFs | 144 | 134 |
| Long-Document Summarization | 156 | 148 |
| Short-Form Summarization | 131 | 116 |
| Blog Post Writing | 139 | 129 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →