Compare / head-to-head
Claude Sonnet 5.5vs
DeepSeek V3.1
Claude Sonnet 5.5 leads 2 of 2 shared benchmarks. Claude Sonnet 5.5 has the larger context window (1M tokens).
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
2 – 0
Claude Sonnet 5.5 leads
Cheaper per token
—
list price, input + output
Larger context
Claude Sonnet 5.5
1M tokens
Providers
2 providers
Anthropic · DeepSeek
Claude Sonnet 5.5
Anthropic · released 2026-09-28
textvision
DeepSeek V3.1
DeepSeek · released 2025-08-21
text
- Context
- 128K
- Max out
- —
- Input /1M
- —
- Output /1M
- —
- Cached /1M
- —
- Scores
- 18 · 9 core
Quality
Benchmark matrix
2 shared · 27 only Claude Sonnet 5.5 · 16 only DeepSeek V3.1| Benchmark | Claude Sonnet 5.5 | DeepSeek V3.1 | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 2 | ||||
| LMArena Elo | 1471 ↗ | 1417.1 ↗ | +53.9 | Claude Sonnet 5.5 |
| SimpleBench (SimpleBench) | 75.9% ↗ | 40% ↗ | +35.9 pt | Claude Sonnet 5.5 |
| Only Claude Sonnet 5.5 reports · 27 | ||||
| GPQA Diamond | 95.6% ↗epoch run | not reported | — | — |
| APEX-Agents (Mercor) | 75.5% ↗ | not reported | — | — |
| Chartography (no tools) | 61.6% ↗ | not reported | — | — |
| CursorBench 4.0 | 55.5% ↗ | not reported | — | — |
| FrontierCode v1.1 (Main) | 46.2% ↗ | not reported | — | — |
| FrontierMath Tier 4 v2 (Epoch AI run) | 80.5% ↗epoch run | not reported | — | — |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 88.8% ↗epoch run | not reported | — | — |
| FrontierSWE V2 (Proximal Labs) | 61.9% ↗ | not reported | — | — |
| Furniture Assembly (Epoch AI run) | 75% ↗epoch run | not reported | — | — |
| Humanity's Last Exam (with tools) | 64.5% ↗ | not reported | — | — |
| LiveBench Agentic Coding (LiveBench) | 56.3% ↗ | not reported | — | — |
| LiveBench Coding (LiveBench) | 91.4% ↗ | not reported | — | — |
| LiveBench Data Analysis (LiveBench) | 78.6% ↗ | not reported | — | — |
| LiveBench Instruction Following (LiveBench) | 70.5% ↗ | not reported | — | — |
| LiveBench Language (LiveBench) | 83.4% ↗ | not reported | — | — |
| LiveBench Mathematics (LiveBench) | 96.7% ↗ | not reported | — | — |
| LiveBench Reasoning (LiveBench) | 91.6% ↗ | not reported | — | — |
| LMArena Agent (LMArena) | 0.1252 ↗ | not reported | — | — |
| LMArena Vision (LMArena) | 1268.3 ↗ | not reported | — | — |
| LMArena WebDev (LMArena) | 1786.3 ↗ | not reported | — | — |
| Mystery Game Puzzles (Epoch AI run) | 65% ↗epoch run | not reported | — | — |
| OSWorld 2.1 (partial) | 80.1% ↗ | not reported | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 100% ↗epoch run | not reported | — | — |
| SAGE (Vals AI) | 51.8% ↗ | not reported | — | — |
| SimpleQA Verified | 46.5% ↗epoch run | not reported | — | — |
| Terminal-Bench 4.0 | 70.6% ↗ | not reported | — | — |
| Terminal-Bench 4.0 (Vals AI) | 64.1% ↗ | not reported | — | — |
| Only DeepSeek V3.1 reports · 16 | ||||
| Aider-Polyglot (thinking) | not reported | 76.3% ↗ | — | — |
| AIME 2024 (thinking) | not reported | 93.1% ↗ | — | — |
| AIME 2025 (thinking) | not reported | 88.4% ↗ | — | — |
| BrowseComp | not reported | 30% ↗ | — | — |
| GPQA-Diamond (thinking) | not reported | 80.1% ↗ | — | — |
| HMMT 2025 (thinking) | not reported | 84.2% ↗ | — | — |
| Humanity's Last Exam (Python + Search) | not reported | 29.8% ↗ | — | — |
| Humanity's Last Exam (thinking, text-only) | not reported | 15.9% ↗ | — | — |
| LiveCodeBench (2408-2505) (thinking) | not reported | 74.8% ↗ | — | — |
| MMLU-Pro (thinking) | not reported | 84.8% ↗ | — | — |
| MMLU-Redux (thinking) | not reported | 93.7% ↗ | — | — |
| SimpleQA (search agent) | not reported | 93.4% ↗ | — | — |
| SWE Verified (Agent mode) | not reported | 66% ↗ | — | — |
| SWE-bench Multilingual (Agent mode) | not reported | 54.5% ↗ | — | — |
| Terminal-bench (Terminus 1 framework) | not reported | 31.3% ↗ | — | — |
| WeirdML (Håvard Tveit Ihle) | not reported | 38.4% ↗ | — | — |
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is Claude Sonnet 5.5 minus DeepSeek V3.1 in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | Claude Sonnet 5.5 | DeepSeek V3.1 | Edge |
|---|---|---|---|
| Context window | 1M tokens | 128K tokens | Claude Sonnet 5.5 |
| Max output | 128K tokens | — | — |
| Input price / 1M | $2 ↗ | — | — |
| Output price / 1M | $10 ↗ | — | — |
| Cached input / 1M | $0.2 ↗ | — | — |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $12 | — | — |
| Modalities | text · vision | text | Claude Sonnet 5.5 |
| Released | 2026-09-28 | 2025-08-21 | — |
| Cited benchmark scores | 29 | 18 | — |
Reliability
Provider status
Live from /statusMore matchups
Claude Sonnet 5.5 vs …
Models sharing the most benchmarksMore matchups
DeepSeek V3.1 vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run Claude Sonnet 5.5 and DeepSeek V3.1 on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.