Anthropic: Claude Sonnet 5.5 vs DeepSeek: DeepSeek V4.1 Flash (batch)
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-09-29.
| Anthropic: Claude Sonnet 5.5 | DeepSeek: DeepSeek V4.1 Flash (batch) | |
|---|---|---|
| Vendor | anthropic | deepseek |
| Quality Score | 100 | 100 |
| Benchmark Score | 97.0 | 66.3 |
| Input Price | $2.00/M | $0.11/M |
| Output Price | $10.00/M | $0.34/M |
| Context Window | 1,000,000 | 1,048,576 |
| Max Output | 128,000 | 131,072 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
| Benchmark Scores | ||
| ai_index | 92.4 | 65.1 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, DeepSeek V4.1 Flash (batch) costs $0.20 and Claude Sonnet 5.5 costs $4.50, so DeepSeek V4.1 Flash (batch) is about 23.0 times cheaper for the same work.
Both take in a similar amount of text: 1,000,000 and 1,048,576 tokens, about 1,500 and 1,573 pages.
On our blended benchmark score Claude Sonnet 5.5 leads 97.0 to 66.3.
Across the 20 tasks where they differ, Claude Sonnet 5.5 scores higher on 15 (SQL Generation, Code Review, Code Refactoring and others), DeepSeek V4.1 Flash (batch) on 5 (Code Completion, CSV / Spreadsheet Cleanup, JSON Extraction and others).
Pick Claude Sonnet 5.5 if you need benchmark performance or the stronger all-round task scores; pick DeepSeek V4.1 Flash (batch) 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 | Anthropic: Claude Sonnet 5.5 | DeepSeek: DeepSeek V4.1 Flash (batch) |
|---|---|---|
| SQL Generation | 143 | 141 |
| Code Review | 149 | 144 |
| Code Completion | 119 | 133 |
| Code Refactoring | 150 | 146 |
| Bug Fixing | 153 | 148 |
| Unit Test Generation | 135 | 131 |
| Code Documentation | 137 | 137 |
| Regex Writing | 126 | 126 |
| CI/CD Pipelines | 131 | 127 |
| Frontend Component Design | 133 | 129 |
| Data Analysis | 137 | 133 |
| CSV / Spreadsheet Cleanup | 136 | 136 |
| ETL Scripting | 140 | 137 |
| JSON Extraction | 121 | 131 |
| Bulk Data Labeling | 118 | 129 |
| OCR / Document Parsing | 135 | 134 |
| Table Extraction from PDFs | 135 | 134 |
| Long-Document Summarization | 151 | 148 |
| Short-Form Summarization | 118 | 127 |
| Blog Post Writing | 131 | 129 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →