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Claude Opus 5.5 vs DeepSeek V4.1 Flash

Claude Opus 5.5 leads DeepSeek V4.1 Flash on coding, 88.8 to 62.5 on the Vibe Coding Index, and DeepSeek V4.1 Flash costs 23.8x less per output token ($0.84 vs $20.00 per million). Updated October 22, 2026; 92 benchmarks have a result for both.

Replace Claude Opus 5.5 Replace DeepSeek V4.1 Flash
Claude Opus 5.5Anthropic
Coding
88.8
Overall
87.1
Output $/M
$20.00
89
DeepSeek V4.1 FlashDeepSeek
Coding
62.5
Overall
62.4
Output $/M
$0.84
3
vs boards won of 92 shared

Claude Opus 5.5 or DeepSeek V4.1 Flash: which to pick

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 62.5 for DeepSeek V4.1 Flash.

Pick DeepSeek V4.1 Flash for output tokens 23.8x cheaper ($0.84 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BDeepSeek V4.1 FlashDeepSeek62.5/1005 independent benchmarksNo cost per solved task
Shared results
92
Claude Opus 5.5 only
17
DeepSeek V4.1 Flash only
9
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Opus 5.5 88.8 from 5 benchmarks, DeepSeek V4.1 Flash 62.5 from 5 benchmarks.
Widest category
Math, 25.2 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Claude Opus 5.5 95.0% against DeepSeek V4.1 Flash 26.8%, 68.2 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against DeepSeek V4.1 Flash $0.84 per million output tokens, 23.8x apart.
Context window
Claude Opus 5.5 takes 1M tokens, DeepSeek V4.1 Flash 1.05M.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Opus 5.5BarsDeepSeek V4.1 FlashTies
Coding190
Intelligence20
Agentic work102
Reasoning130
Math60
Knowledge60
Web design80
General251
All shared boards893
CodingLike-for-likeSix of these boards feed the Vibe Coding Index190
Coding benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
LiveBench coding96.3%90.2%Claude Opus 5.5
LMArena WebDev18071618Claude Opus 5.5
Terminal-Bench 4 (Vals AI)65.2%19.7%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%84.7%Claude Opus 5.5
Code migration (Vals AI)66.7%45.6%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.5%Claude Opus 5.5
IOI (Vals AI)95.1%40.3%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%74.5%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%46.5%Claude Opus 5.5
Vibe Code Bench 1-100 (Vals AI)30.4%16.4%Claude Opus 5.5
SkillsBench (Vals AI)Not measured69.8%Only DeepSeek V4.1 Flash measured
CyberBench (Vals AI)74.6%73.7%Claude Opus 5.5
SciCode66.9%51.9%Claude Opus 5.5
FrontierCode54.6%43.9%Claude Opus 5.5
FrontierSWE62.3%Not measuredOnly Claude Opus 5.5 measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.41092.3Claude Opus 5.5
LMArena Text: coding15451502Claude Opus 5.5
LMArena Text: software and IT15381496Claude Opus 5.5
LMArena WebDev: React18551628Claude Opus 5.5
LMArena WebDev: HTML17531612Claude Opus 5.5
LMArena WebDev: from an image17531606Claude Opus 5.5
SciCode18.5%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 16 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
AA Intelligence Index57.624.7Claude Opus 5.5
Epoch Capabilities Index168.8155.9Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index102
Agentic work benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
Design Arena: agents building web apps1316Not measuredOnly Claude Opus 5.5 measured
Design Arena: agents building mobile apps1308Not measuredOnly Claude Opus 5.5 measured
Design Arena: spreadsheets1368Not measuredOnly Claude Opus 5.5 measured
LiveBench research85.0%86.8%DeepSeek V4.1 Flash
LiveBench browser80.0%84.0%DeepSeek V4.1 Flash
LiveBench long agentic85.0%40.1%Claude Opus 5.5
SREBench (Vals AI)33.6%0.8%Claude Opus 5.5
Finance Agent (Vals AI)58.6%53.5%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%26.6%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%41.4%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%Not measuredOnly Claude Opus 5.5 measured
Excel Modeling Benchmark (Vals AI)75.9%57.2%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%67.8%Claude Opus 5.5
Terminal-Bench-Science (Vals AI)47.1%0.0%Claude Opus 5.5
Vals Science Index58.7%29.6%Claude Opus 5.5
Time Horizon Index (Vals AI)91.3%Not measuredOnly Claude Opus 5.5 measured
CUA-bench (Vals AI)14.0%Not measuredOnly Claude Opus 5.5 measured
Robo-bench (Vals AI)14.6%Not measuredOnly Claude Opus 5.5 measured
APEX-Agents73.5%39.5%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235Not measuredOnly Claude Opus 5.5 measured
LMArena Search1213Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 18 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index130
Reasoning benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
LiveBench reasoning92.2%86.7%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%21.2%Claude Opus 5.5
Humanity's Last Exam (Artificial Analysis run)61.4%39.2%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%89.8%Claude Opus 5.5
ARC-AGI98.5%94.5%Claude Opus 5.5
ARC-AGI-293.3%72.9%Claude Opus 5.5
Chess puzzles67.0%48.0%Claude Opus 5.5
Mystery game puzzles71.0%43.0%Claude Opus 5.5
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361483Claude Opus 5.5
LMArena Text: expert15491501Claude Opus 5.5
LMArena Text: hard prompts in English15351488Claude Opus 5.5
LMArena Vision: diagrams13451297Claude Opus 5.5
LMArena Vision: homework13621307Claude Opus 5.5
Neither model has a result on the other 8 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
OTIS Mock AIME100.0%98.3%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%67.4%Claude Opus 5.5
FrontierMath, tier 495.0%26.8%Claude Opus 5.5
ProofBench100.0%54.0%Claude Opus 5.5
LMArena Text: math15181478Claude Opus 5.5
LMArena Text: mathematical work15161485Claude Opus 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
LegalBench (Vals AI)Not measured83.3%Only DeepSeek V4.1 Flash measured
MedCode (Vals AI)49.8%41.2%Claude Opus 5.5
SimpleQA Verified72.2%42.9%Claude Opus 5.5
LMArena Text: science15241469Claude Opus 5.5
LMArena Text: medicine and healthcare15091484Claude Opus 5.5
LMArena Text: legal and government15181443Claude Opus 5.5
LMArena Text: business and finance14941461Claude Opus 5.5
FACTS Benchmark Suite65.3%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 10 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
Design Arena: websites13351308Claude Opus 5.5
Design Arena: UI components13851312Claude Opus 5.5
Design Arena: game dev14611330Claude Opus 5.5
Design Arena: data viz13971291Claude Opus 5.5
Design Arena: 3D14761355Claude Opus 5.5
Design Arena: all code categories13901320Claude Opus 5.5
Design Arena: SVG13291245Claude Opus 5.5
Design Arena: ASCII artNot measured1265Only DeepSeek V4.1 Flash measured
LiveBench design86.9%79.2%Claude Opus 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index251
General benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
Vals Index70.2%Not measuredOnly Claude Opus 5.5 measured
LiveBench data analysis80.3%79.3%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%64.3%Claude Opus 5.5
SAGE (Vals AI)45.8%47.9%DeepSeek V4.1 Flash
MedScribe (Vals AI)91.4%85.5%Claude Opus 5.5
Long context reasoning (AA-LCR)84.7%84.0%Claude Opus 5.5
DTBench98.9%89.9%Claude Opus 5.5
LMCA68.2%47.0%Claude Opus 5.5
Surface Evolver BenchNot measured46.3%Only DeepSeek V4.1 Flash measured
Furniture assembly83.3%34.2%Claude Opus 5.5
LMArena Text15161464Claude Opus 5.5
LMArena Text: instruction following15371473Claude Opus 5.5
LMArena Text: creative writing15351437Claude Opus 5.5
LMArena Vision13211278Claude Opus 5.5
LMArena Text: English15191473Claude Opus 5.5
LMArena Text: non-English15071449Claude Opus 5.5
LMArena Text: Chinese15821501Claude Opus 5.5
LMArena Text: GermanNot measured1470Only DeepSeek V4.1 Flash measured
LMArena Text: Japanese15341432Claude Opus 5.5
LMArena Text: KoreanNot measured1436Only DeepSeek V4.1 Flash measured
LMArena Text: French14931465Claude Opus 5.5
LMArena Text: Spanish15081459Claude Opus 5.5
LMArena Text: Russian15171467Claude Opus 5.5
LMArena Text: PolishNot measured1457Only DeepSeek V4.1 Flash measured
LMArena Text: multi-turn15011461Claude Opus 5.5
LMArena Text: longer queries15321473Claude Opus 5.5
LMArena Text: writing and language15321450Claude Opus 5.5
LMArena Text: entertainment and media15151445Claude Opus 5.5
LMArena Vision: English13171288Claude Opus 5.5
LMArena Vision: ChineseNot measured1327Only DeepSeek V4.1 Flash measured
LMArena Vision: reading text13261282Claude Opus 5.5
LMArena Vision: humorNot measured1260Only DeepSeek V4.1 Flash measured
LMArena Vision: creative writing13201275Claude Opus 5.5
Neither model has a result on the other 13 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 5.5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5.5DeepSeek V4.1 FlashLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Opus 5.5$0.014Fits in one request
DeepSeek V4.1 Flash$0.0006Fits in one request

DeepSeek V4.1 Flash costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
DeepSeek V4.1 Flash$0.014Fits in one request

DeepSeek V4.1 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits in one request
DeepSeek V4.1 Flash$0.053Fits in one request

DeepSeek V4.1 Flash costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Opus 5.5 and DeepSeek V4.1 Flash
SpecificationAnthropic Claude Opus 5.5DeepSeek V4.1 Flash
MakerAnthropicDeepSeek
WeightsNo public weights listedOpen weights
ReleasedSeptember 22, 2026September 10, 2026
Context window1M1.05M
Input $/Mtok$4.00$0.2225
Output $/Mtok$20.00$0.84
Coding index88.862.5
Independent measurements behind it55
Cost per solved taskNot computableNot computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than DeepSeek V4.1 Flash for coding?

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 62.5 for DeepSeek V4.1 Flash. Pick DeepSeek V4.1 Flash for output tokens 23.8x cheaper ($0.84 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Opus 5.5 or DeepSeek V4.1 Flash?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; DeepSeek V4.1 Flash costs $0.2225 and $0.84. Cost per solved task is known for neither of them.

Which has the bigger context window, Claude Opus 5.5 or DeepSeek V4.1 Flash?

DeepSeek V4.1 Flash, with 1.05M tokens against 1M.

How many benchmarks is the Claude Opus 5.5 vs DeepSeek V4.1 Flash comparison based on?

92 benchmarks have a result for both models as of October 22, 2026. Claude Opus 5.5's coding index rests on 5 independent benchmarks and DeepSeek V4.1 Flash's on 5. Where only one model has a result, the page says so instead of naming a winner.

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