OpenAI: GPT-5.3-Codex vs Anthropic: Claude Sonnet 4.6
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| OpenAI: GPT-5.3-Codex | Anthropic: Claude Sonnet 4.6 | |
|---|---|---|
| Vendor | openai | anthropic |
| Quality Score | 100 | 100 |
| Benchmark Score | 73.4 | 80.1 |
| Input Price | $1.75/M | $3.00/M |
| Output Price | $14.00/M | $15.00/M |
| Context Window | 400,000 | 1,000,000 |
| Max Output | 128,000 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 73.0 | 77.9 |
| ai_index_agentic | - | 67.3 |
| ai_index_coding | - | 100.0 |
| aider_polyglot | - | 61.3 |
| eqbench | - | 68.4 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-5.3-Codex costs $5.25 and Claude Sonnet 4.6 costs $6.75, so GPT-5.3-Codex is about 1.3 times cheaper for the same work.
Claude Sonnet 4.6 reads up to 1,000,000 tokens at once, roughly 1,500 pages of text, against about 600 pages for GPT-5.3-Codex.
On our blended benchmark score Claude Sonnet 4.6 leads 80.1 to 73.4.
Across the 20 tasks where they differ, Claude Sonnet 4.6 on 20 (SQL Generation, Code Review, Code Completion and others).
Pick GPT-5.3-Codex if you need lower cost; pick Claude Sonnet 4.6 if you need 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-5.3-Codex | Anthropic: Claude Sonnet 4.6 |
|---|---|---|
| SQL Generation | 141 | 183 |
| Code Review | 145 | 183 |
| Code Completion | 118 | 120 |
| Code Refactoring | 147 | 179 |
| Bug Fixing | 149 | 196 |
| Unit Test Generation | 132 | 166 |
| Code Documentation | 135 | 148 |
| Regex Writing | 124 | 139 |
| CI/CD Pipelines | 128 | 155 |
| Frontend Component Design | 130 | 154 |
| Data Analysis | 134 | 183 |
| CSV / Spreadsheet Cleanup | 135 | 163 |
| ETL Scripting | 138 | 167 |
| JSON Extraction | 120 | 142 |
| Bulk Data Labeling | 117 | 124 |
| OCR / Document Parsing | 134 | 152 |
| Table Extraction from PDFs | 134 | 152 |
| Long-Document Summarization | 148 | 172 |
| Short-Form Summarization | 116 | 124 |
| Blog Post Writing | 129 | 147 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →