Model comparison
Claude Opus 5.5 vs DeepSeek V4 Flash
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 53.6 on the Noometry Index. DeepSeek V4 Flash costs 30× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 33 shared benchmarks.
DeepSeekSummary
- They share 33 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and DeepSeek V4 Flash in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 60.3.
- The biggest single-benchmark swing is FrontierMath Tier 4: 95% for Claude Opus 5.5 and 24.4% for DeepSeek V4 Flash.
- DeepSeek V4 Flash is cheaper at $0.15 / $0.60 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- DeepSeek V4 Flash has downloadable open weights; the other is API-only.
Side by side
| Claude Opus 5.5 | DeepSeek V4 Flash | |
|---|---|---|
| Provider | Anthropic | DeepSeek |
| Noometry Index | 68.6 | 53.6 |
| Released | 2026-09-22 | 2026-04-24 |
| Weights | Proprietary | Open |
| Context window | 1M | 1M |
| Max output | 128K | 393K |
| Input $ / M tokens | $4 | $0.15 |
| Output $ / M tokens | $20 | $0.60 |
| Results tracked | 44 | 41 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.9 (#3), DeepSeek V4 Flash: 47.9 (#59)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| FrontierCode | 54.6% | 18.8% |
| LMArena WebDev | 1813 | 1582 |
| SciCode | 66.9% | 49.9% |
| LMArena Coding | 1547 | 1457 |
| ALE-Bench | 2,147 | 1,306 |
| CursorBench | 57.8% | — |
| FrontierSWE | 62.3% | — |
| WeirdML | — | 63% |
| MirrorCode | 77.4% | — |
Agentic & Tool Use Not comparable
Claude Opus 5.5: 45.3 (#15), DeepSeek V4 Flash: —
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| APEX-Agents | 73.5% | — |
| GDP.pdf | 30.6% | — |
| Vending-Bench 2 | 9,235 | — |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 80.2 (#3), DeepSeek V4 Flash: 53.7 (#30)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| ARC-AGI-2 | 93.3% | 61.4% |
| NYT Connections (extended) | 88.5% | 89.6% |
| ARC-AGI-1 | 98.5% | 89% |
| CritPt | 31.7% | 16.6% |
| LMArena Hard Prompts | 1535 | 1444 |
| Mystery Game Puzzles | 71% | 34% |
| DTBench | 98.9% | 90.9% |
| LMCA | 68.2% | 41.7% |
| Epoch Capabilities Index | 167.33 | 154.49 |
| SimpleBench | — | 61.1% |
| Kagi LLM Benchmark | — | 52.2% |
| Chess Puzzles | — | 33% |
| EBR-Bench | 71.4% | — |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 91.8 (#3), DeepSeek V4 Flash: 60.3 (#37)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 57.5% |
| FrontierMath Tier 4 | 95% | 24.4% |
| OTIS Mock AIME 2024-2025 | 100% | 94.4% |
| ProofBench | 100% | 56% |
| LMArena Math | 1506 | 1427 |
| MathArena Final-Answer Competitions | — | 76.5% |
| FrontierMath Erdős | 2.9% | — |
Knowledge Claude Opus 5.5 leads
Claude Opus 5.5: 66.4 (#10), DeepSeek V4 Flash: 55.4 (#48)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| GPQA Diamond | 90.6% | 91% |
| SimpleQA Verified | 72.2% | 33.6% |
| LMArena Expert | 1547 | 1441 |
Multimodal Not comparable
Claude Opus 5.5: 57.8 (#1), DeepSeek V4 Flash: —
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| LMArena Vision | 1321 | — |
| Blueprint-Bench 2 | 51.2% | — |
| Furniture Assembly | 83.3% | — |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.1 (#2), DeepSeek V4 Flash: 53.0 (#72)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| LMArena Non-English | 1507 | 1420 |
| LMArena Chinese | 1588 | 1468 |
| LMArena French | 1514 | 1439 |
| LMArena Russian | 1520 | 1428 |
| LMArena Spanish | 1507 | 1436 |
| LMArena German | — | 1418 |
| LMArena Japanese | — | 1406 |
| LMArena Korean | — | 1384 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.0 (#3), DeepSeek V4 Flash: 74.9 (#81)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| LMArena Instruction Following | 1537 | 1421 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.1 (#19), DeepSeek V4 Flash: 43.8 (#85)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| LMArena Longer Query | 1532 | 1434 |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.2 (#3), DeepSeek V4 Flash: 63.8 (#61)
| Benchmark | Claude Opus 5.5 | DeepSeek V4 Flash |
|---|---|---|
| LMArena Text | 1515 | 1432 |
| LMArena Creative Writing | 1533 | 1403 |
| EQ-Bench Creative Writing | 2050 | 1559 |
| LMArena Multi-Turn | 1499 | 1449 |
Frequently asked questions
Is Claude Opus 5.5 better than DeepSeek V4 Flash?
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 53.6 on the Noometry Index. DeepSeek V4 Flash costs 30× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 5.5 or DeepSeek V4 Flash?
DeepSeek V4 Flash is cheaper. It lists at $0.15 per million input tokens and $0.60 per million output tokens; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or DeepSeek V4 Flash better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 47.9 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 5.5 and DeepSeek V4 Flash share?
33 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and DeepSeek V4 Flash has 41.