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Claude Opus 5 vs DeepSeek V4.1 Flash

Updated October 21, 2026. 99 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Opus 5 Replace DeepSeek V4.1 Flash
Claude Opus 5Anthropic
Coding
81.8
Overall
50.8
Output $/M
$25.00
91
DeepSeek V4.1 FlashDeepSeek
Coding
77.2
Overall
24.7
Output $/M
$0.525
6
vs boards won of 99 shared, 2 tied

Decision reading

Pick Claude Opus 5 for coding: it scores 81.8 on the Vibe Coding Index against 77.2 for DeepSeek V4.1 Flash.

Pick DeepSeek V4.1 Flash when output tokens cost 47.6x less, or when the context window is larger, 1.05M against 1M tokens.

Model AClaude Opus 5Anthropic81.8/1002 independent benchmarks$1.33 per solved taskModel BDeepSeek V4.1 FlashDeepSeek77.2/1002 independent benchmarksNo cost per solved task
Shared results
99
Claude Opus 5 only
31
DeepSeek V4.1 Flash only
2
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

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 81.8 from 2 benchmarks, DeepSeek V4.1 Flash 77.2 from 2 benchmarks.
Widest category
Math, 21.5 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Claude Opus 5 73.2% against DeepSeek V4.1 Flash 26.8%, 46.3 points apart on a 0 to 100 scale.
Output price
Claude Opus 5 $25.00 against DeepSeek V4.1 Flash $0.525 per million output tokens, 47.6x apart.
Context window
Claude Opus 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 5BarsDeepSeek V4.1 FlashTies
Coding172
Intelligence20
Agentic work1101 tie
Reasoning121
Math60
Knowledge70
Web design711 tie
General292
All shared boards9162 ties
CodingLike-for-likeFour of these boards feed the Vibe Coding Index172
Coding benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
LiveBench coding90.8%90.2%Claude Opus 5
LMArena WebDev16891618Claude Opus 5
AA Coding Index78.0Not measuredOnly Claude Opus 5 measured
LiveCodeBench (Vals AI)89.0%Not measuredOnly Claude Opus 5 measured
SWE-bench Verified (Vals AI)97.0%Not measuredOnly Claude Opus 5 measured
Terminal-Bench 4 (Vals AI)53.5%19.7%Claude Opus 5
Vibe Code Bench (Vals AI)88.4%84.7%Claude Opus 5
Code migration (Vals AI)57.5%45.6%Claude Opus 5
ProgramBench (Vals AI)3.0%0.5%Claude Opus 5
IOI (Vals AI)84.3%40.3%Claude Opus 5
Terminal-Bench 2.1 (Vals AI)84.6%74.5%Claude Opus 5
SWE-bench Multimodal (Vals AI)Not measured46.5%Only DeepSeek V4.1 Flash measured
Vibe Code Bench 1-100 (Vals AI)28.5%16.4%Claude Opus 5
SkillsBench (Vals AI)60.4%69.8%DeepSeek V4.1 Flash
CyberBench (Vals AI)65.4%73.7%DeepSeek V4.1 Flash
SciCode56.4%51.9%Claude Opus 5
FrontierCode53.4%43.9%Claude Opus 5
FrontierSWE52.0%Not measuredOnly Claude Opus 5 measured
WeirdML91.8%Not measuredOnly Claude Opus 5 measured
ALE-Bench2164.61092.3Claude Opus 5
LMArena Text: coding15331502Claude Opus 5
LMArena Text: software and IT15271496Claude Opus 5
LMArena WebDev: React17111628Claude Opus 5
LMArena WebDev: HTML16801612Claude Opus 5
LMArena WebDev: from an image16621606Claude Opus 5
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
AA Intelligence Index50.824.7Claude Opus 5
Epoch Capabilities Index163.9155.9Claude Opus 5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index110
Agentic work benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
AA Agentic Index56.5Not measuredOnly Claude Opus 5 measured
Design Arena: agents building web apps1266Not measuredOnly Claude Opus 5 measured
Design Arena: agents building full-stack apps1306Not measuredOnly Claude Opus 5 measured
Design Arena: agents building mobile apps1348Not measuredOnly Claude Opus 5 measured
Design Arena: agents building Android apps1258Not measuredOnly Claude Opus 5 measured
Design Arena: agents building Godot games1279Not measuredOnly Claude Opus 5 measured
Design Arena: agents building games1261Not measuredOnly Claude Opus 5 measured
Design Arena: PowerPoint slides1265Not measuredOnly Claude Opus 5 measured
LiveBench research88.9%86.8%Claude Opus 5
LiveBench browser84.0%84.0%Tie
LiveBench long agentic62.1%40.1%Claude Opus 5
SREBench (Vals AI)12.2%0.8%Claude Opus 5
Finance Agent (Vals AI)58.6%53.5%Claude Opus 5
Tax Agent Bench (Vals AI)45.5%26.6%Claude Opus 5
Legal Research Bench (Vals AI)55.3%41.4%Claude Opus 5
Excel Modeling Benchmark (Vals AI)73.6%57.2%Claude Opus 5
BioMysteryBench (Vals AI)79.3%67.8%Claude Opus 5
Terminal-Bench-Science (Vals AI)27.1%0.0%Claude Opus 5
Vals Science Index47.9%29.6%Claude Opus 5
Time Horizon Index (Vals AI)18.8%Not measuredOnly Claude Opus 5 measured
CUA-bench (Vals AI)9.0%Not measuredOnly Claude Opus 5 measured
APEX-Agents65.8%39.5%Claude Opus 5
OSWorld 2.031.4%Not measuredOnly Claude Opus 5 measured
BALROG63.4%Not measuredOnly Claude Opus 5 measured
PostTrainBench35.0%Not measuredOnly Claude Opus 5 measured
Vending-Bench 2$11,182Not measuredOnly Claude Opus 5 measured
LMArena Search1242Not measuredOnly Claude Opus 5 measured
Neither model has a result on the other 12 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index121
Reasoning benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
GPQA Diamond93.4%Not measuredOnly Claude Opus 5 measured
LiveBench reasoning91.2%86.7%Claude Opus 5
MysteryMechanism (Vals AI)37.4%21.2%Claude Opus 5
MMMU Pro (Vals AI)89.9%Not measuredOnly Claude Opus 5 measured
GPQA Diamond (Artificial Analysis run)93.7%Not measuredOnly Claude Opus 5 measured
Humanity's Last Exam (Artificial Analysis run)54.9%39.2%Claude Opus 5
GPQA Diamond (Epoch AI run)93.9%89.8%Claude Opus 5
ARC-AGI97.5%94.5%Claude Opus 5
ARC-AGI-290.4%72.9%Claude Opus 5
SimpleBench80.6%Not measuredOnly Claude Opus 5 measured
Chess puzzles43.0%48.0%DeepSeek V4.1 Flash
Mystery game puzzles59.0%43.0%Claude Opus 5
EBR-bench45.7%Not measuredOnly Claude Opus 5 measured
LMArena Text: hard prompts15271483Claude Opus 5
LMArena Text: expert15541501Claude Opus 5
LMArena Text: hard prompts in English15231488Claude Opus 5
LMArena Vision: diagrams13481297Claude Opus 5
LMArena Vision: homework13381307Claude Opus 5
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
OTIS Mock AIME98.9%98.3%Claude Opus 5
FrontierMath, tiers 1 to 385.6%67.4%Claude Opus 5
FrontierMath, tier 473.2%26.8%Claude Opus 5
ProofBench99.0%54.0%Claude Opus 5
LMArena Text: math15331478Claude Opus 5
LMArena Text: mathematical work15441485Claude Opus 5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70
Knowledge benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
MMLU Pro91.6%Not measuredOnly Claude Opus 5 measured
LegalBench (Vals AI)87.0%83.3%Claude Opus 5
CorpFin (Vals AI)73.2%Not measuredOnly Claude Opus 5 measured
TaxEval (Vals AI)75.1%Not measuredOnly Claude Opus 5 measured
MortgageTax (Vals AI)72.1%Not measuredOnly Claude Opus 5 measured
MedCode (Vals AI)63.6%41.2%Claude Opus 5
SimpleQA Verified59.9%42.9%Claude Opus 5
LMArena Text: science15311469Claude Opus 5
LMArena Text: medicine and healthcare15251484Claude Opus 5
LMArena Text: legal and government15301443Claude Opus 5
LMArena Text: business and finance15011461Claude Opus 5
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index71
Web design benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
Design Arena: websites13091309Tie
Design Arena: UI components13481314Claude Opus 5
Design Arena: game dev13391331Claude Opus 5
Design Arena: data viz13291290Claude Opus 5
Design Arena: 3D13351356DeepSeek V4.1 Flash
Design Arena: all code categories13241320Claude Opus 5
Design Arena: SVG13101243Claude Opus 5
Design Arena: ASCII art13521265Claude Opus 5
LiveBench design83.0%79.2%Claude Opus 5
GeneralLike-for-likePublic boards, shown as published, kept out of the index292
General benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 5DeepSeek V4.1 FlashLeader
LiveBench data analysis74.6%79.3%DeepSeek V4.1 Flash
Public Benefits Bench (Vals AI)76.9%64.3%Claude Opus 5
SAGE (Vals AI)49.4%47.9%Claude Opus 5
MedScribe (Vals AI)91.0%85.5%Claude Opus 5
Vals Multimodal Index73.9%Not measuredOnly Claude Opus 5 measured
Long context reasoning (AA-LCR)82.0%84.0%DeepSeek V4.1 Flash
DTBench97.9%89.9%Claude Opus 5
LMCA64.5%47.0%Claude Opus 5
Surface Evolver BenchNot measured46.3%Only DeepSeek V4.1 Flash measured
Furniture assembly60.8%34.2%Claude Opus 5
LMArena Text15091464Claude Opus 5
LMArena Text: instruction following15181473Claude Opus 5
LMArena Text: creative writing14931437Claude Opus 5
LMArena Vision13201278Claude Opus 5
LMArena Text: English15081473Claude Opus 5
LMArena Text: non-English15021449Claude Opus 5
LMArena Text: Chinese15731501Claude Opus 5
LMArena Text: German15271470Claude Opus 5
LMArena Text: Japanese15201432Claude Opus 5
LMArena Text: Korean15171436Claude Opus 5
LMArena Text: French15191465Claude Opus 5
LMArena Text: Spanish15231459Claude Opus 5
LMArena Text: Russian15071467Claude Opus 5
LMArena Text: Polish15221457Claude Opus 5
LMArena Text: multi-turn15001461Claude Opus 5
LMArena Text: longer queries15171473Claude Opus 5
LMArena Text: writing and language14991450Claude Opus 5
LMArena Text: entertainment and media14811445Claude Opus 5
LMArena Vision: English13151288Claude Opus 5
LMArena Vision: Chinese14001327Claude Opus 5
LMArena Vision: reading text13291282Claude Opus 5
LMArena Vision: humor12931260Claude Opus 5
LMArena Vision: creative writing13131275Claude Opus 5
LMArena Document1516Not measuredOnly Claude Opus 5 measured
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 5 and DeepSeek V4.1 Flash
BenchmarkClaude Opus 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$0.018Fits in one request
DeepSeek V4.1 Flash$0.0003Fits in one request

DeepSeek V4.1 Flash costs less

Repository review

50K input + 3K output tokens

Claude Opus 5$0.325Fits in one request
DeepSeek V4.1 Flash$0.0040Fits in one request

DeepSeek V4.1 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5$1.25Fits in one request
DeepSeek V4.1 Flash$0.015Fits 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 and DeepSeek V4.1 Flash
SpecificationAnthropic Claude Opus 5DeepSeek V4.1 Flash
MakerAnthropicDeepSeek
WeightsNo public weights listedOpen weights
ReleasedJuly 24, 2026September 10, 2026
Context window1M1.05M
Input $/Mtok$5.00$0.049
Output $/Mtok$25.00$0.525
Coding index81.877.2
Independent measurements behind it22
Cost per solved task$1.33Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5 better than DeepSeek V4.1 Flash for coding?

Pick Claude Opus 5 for coding: it scores 81.8 on the Vibe Coding Index against 77.2 for DeepSeek V4.1 Flash. Pick DeepSeek V4.1 Flash when output tokens cost 47.6x less, or when the context window is larger, 1.05M against 1M tokens.

Which is cheaper, Claude Opus 5 or DeepSeek V4.1 Flash?

Claude Opus 5 costs $5.00 per million input tokens and $25.00 per million output tokens; DeepSeek V4.1 Flash costs $0.049 and $0.525. Cost per solved task is known for Claude Opus 5 only.

Which has the bigger context window, Claude Opus 5 or DeepSeek V4.1 Flash?

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

How many benchmarks is the Claude Opus 5 vs DeepSeek V4.1 Flash comparison based on?

99 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5's coding index rests on 2 independent benchmarks and DeepSeek V4.1 Flash's on 2. Where only one model has a result, the page says so instead of naming a winner.

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