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Claude Sonnet 4.5 vs DeepSeek V3.1 Terminus

Claude Sonnet 4.5 leads DeepSeek V3.1 Terminus on the Artificial Analysis Intelligence Index, 20.7 to 14.8, and DeepSeek V3.1 Terminus costs 14.8x less per output token ($1.0142 vs $15.00 per million). Updated October 22, 2026; 33 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace DeepSeek V3.1 Terminus
Claude Sonnet 4.5Anthropic
Coding
39.5
Overall
49.5
Output $/M
$15.00
27
DeepSeek V3.1 TerminusDeepSeek
Coding
No data
Overall
No data
Output $/M
$1.0142
6
vs boards won of 33 shared

Claude Sonnet 4.5 or DeepSeek V3.1 Terminus: which to pick

Only Claude Sonnet 4.5 has a coding score, 39.5 on the Vibe Coding Index; DeepSeek V3.1 Terminus has none, so the two cannot be ranked on coding.

Pick DeepSeek V3.1 Terminus for output tokens 14.8x cheaper ($1.0142 vs $15.00 per million) and work measured by LMArena Text: science or LMArena Text: medicine and healthcare, where it leads.

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BDeepSeek V3.1 TerminusDeepSeekNot benchmarkedNo coding benchmarkNo cost per solved task
Shared results
33
Claude Sonnet 4.5 only
62
DeepSeek V3.1 Terminus only
12
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 Sonnet 4.5 39.5 from 3 benchmarks, DeepSeek V3.1 Terminus not benchmarked.
Widest category
Agentic work, 9.0 points apart on average over 1 shared benchmark.
Widest single gap
LMArena Text: coding: Claude Sonnet 4.5 1488 against DeepSeek V3.1 Terminus 1425, 10.5 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against DeepSeek V3.1 Terminus $1.0142 per million output tokens, 14.8x apart.
Context window
Claude Sonnet 4.5 takes 1M tokens, DeepSeek V3.1 Terminus 164K.

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 Sonnet 4.5BarsDeepSeek V3.1 TerminusTies
Coding30
Intelligence10
Agentic work10
Reasoning30
Math10
Knowledge13
Web design52
General121
All shared boards276
CodingLike-for-likeSix of these boards feed the Vibe Coding Index30
Coding benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
SWE-bench Verified74.8%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LMArena WebDev1394Not measuredOnly Claude Sonnet 4.5 measured
AA Coding Index52.143.5Claude Sonnet 4.5
LiveCodeBench (Vals AI)73.0%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Verified (Vals AI)70.0%Not measuredOnly Claude Sonnet 4.5 measured
Vibe Code Bench (Vals AI)22.6%Not measuredOnly Claude Sonnet 4.5 measured
LiveCodeBench (Artificial Analysis run)Not measured79.8%Only DeepSeek V3.1 Terminus measured
SciCodeNot measured38.0%Only DeepSeek V3.1 Terminus measured
Terminal-Bench Hard (Artificial Analysis run)Not measured31.8%Only DeepSeek V3.1 Terminus measured
Terminal-Bench46.5%Not measuredOnly Claude Sonnet 4.5 measured
GSO-Bench14.7%Not measuredOnly Claude Sonnet 4.5 measured
WeirdML47.7%Not measuredOnly Claude Sonnet 4.5 measured
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured745.2Only DeepSeek V3.1 Terminus measured
LMArena Text: coding14881425Claude Sonnet 4.5
LMArena Text: software and IT14731426Claude Sonnet 4.5
LMArena WebDev: React1386Not measuredOnly Claude Sonnet 4.5 measured
LMArena WebDev: HTML1399Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 20 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
AA Intelligence Index20.714.8Claude Sonnet 4.5
Epoch Capabilities Index146.7Not measuredOnly Claude Sonnet 4.5 measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
Agentic work benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
AA Agentic Index15.86.8Claude Sonnet 4.5
Design Arena: agents building web apps1060Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building full-stack apps1050Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building mobile apps1137Not measuredOnly Claude Sonnet 4.5 measured
τ²-Bench TelecomNot measured37.1%Only DeepSeek V3.1 Terminus measured
METR time horizons67.4%Not measuredOnly Claude Sonnet 4.5 measured
Remote Labor Index2.1%Not measuredOnly Claude Sonnet 4.5 measured
GDPval42.5%Not measuredOnly Claude Sonnet 4.5 measured
DeepResearch Bench52.6%Not measuredOnly Claude Sonnet 4.5 measured
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839Not measuredOnly Claude Sonnet 4.5 measured
Berkeley Function Calling Leaderboard (BFCL)73.2%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 29 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
Reasoning benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
GPQA Diamond81.6%Not measuredOnly Claude Sonnet 4.5 measured
MMMU Pro (Vals AI)79.3%Not measuredOnly Claude Sonnet 4.5 measured
GPQA Diamond (Artificial Analysis run)Not measured79.2%Only DeepSeek V3.1 Terminus measured
Humanity's Last Exam (Artificial Analysis run)Not measured16.4%Only DeepSeek V3.1 Terminus measured
GPQA Diamond (Epoch AI run)82.3%Not measuredOnly Claude Sonnet 4.5 measured
ARC-AGI63.7%Not measuredOnly Claude Sonnet 4.5 measured
ARC-AGI-213.6%Not measuredOnly Claude Sonnet 4.5 measured
SimpleBench54.3%Not measuredOnly Claude Sonnet 4.5 measured
Chess puzzles10.0%Not measuredOnly Claude Sonnet 4.5 measured
Mystery game puzzles17.0%Not measuredOnly Claude Sonnet 4.5 measured
EBR-bench2.4%Not measuredOnly Claude Sonnet 4.5 measured
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621426Claude Sonnet 4.5
LMArena Text: expert1483Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts in English14711432Claude Sonnet 4.5
Kagi LLM Benchmark57.9%57.4%Claude Sonnet 4.5
Neither model has a result on the other 6 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index10
Math benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
AIME88.2%Not measuredOnly Claude Sonnet 4.5 measured
MGSM (Vals AI)94.3%Not measuredOnly Claude Sonnet 4.5 measured
AA Math IndexNot measured89.7Only DeepSeek V3.1 Terminus measured
AIME 2025 (Artificial Analysis run)Not measured89.7%Only DeepSeek V3.1 Terminus measured
OTIS Mock AIME77.8%Not measuredOnly Claude Sonnet 4.5 measured
FrontierMath, tiers 1 to 323.9%Not measuredOnly Claude Sonnet 4.5 measured
FrontierMath, tier 42.4%Not measuredOnly Claude Sonnet 4.5 measured
ProofBench19.0%Not measuredOnly Claude Sonnet 4.5 measured
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491402Claude Sonnet 4.5
LMArena Text: mathematical work1462Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 2 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index13
Knowledge benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
MMLU Pro87.4%Not measuredOnly Claude Sonnet 4.5 measured
LegalBench (Vals AI)84.1%Not measuredOnly Claude Sonnet 4.5 measured
CaseLaw (Vals AI)62.2%Not measuredOnly Claude Sonnet 4.5 measured
CorpFin (Vals AI)62.0%Not measuredOnly Claude Sonnet 4.5 measured
TaxEval (Vals AI)73.3%Not measuredOnly Claude Sonnet 4.5 measured
MortgageTax (Vals AI)64.0%Not measuredOnly Claude Sonnet 4.5 measured
MedQA (Vals AI)94.7%Not measuredOnly Claude Sonnet 4.5 measured
MedCode (Vals AI)44.1%Not measuredOnly Claude Sonnet 4.5 measured
MMLU Pro (Artificial Analysis run)Not measured85.1%Only DeepSeek V3.1 Terminus measured
SimpleQA Verified30.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: science14481451DeepSeek V3.1 Terminus
LMArena Text: medicine and healthcare14441468DeepSeek V3.1 Terminus
LMArena Text: legal and government14511457DeepSeek V3.1 Terminus
LMArena Text: business and finance14401414Claude Sonnet 4.5
FACTS Benchmark Suite40.6%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index52
Web design benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
Design Arena: websites11891187Claude Sonnet 4.5
Design Arena: UI components11701182DeepSeek V3.1 Terminus
Design Arena: game dev11661131Claude Sonnet 4.5
Design Arena: data viz11671168DeepSeek V3.1 Terminus
Design Arena: 3D11571141Claude Sonnet 4.5
Design Arena: all code categories11821175Claude Sonnet 4.5
Design Arena: SVG11151065Claude Sonnet 4.5
Design Arena: ASCII art1205Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index121
General benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
SAGE (Vals AI)36.1%Not measuredOnly Claude Sonnet 4.5 measured
MedScribe (Vals AI)84.5%Not measuredOnly Claude Sonnet 4.5 measured
IFBenchNot measured57.0%Only DeepSeek V3.1 Terminus measured
Long context reasoning (AA-LCR)Not measured69.3%Only DeepSeek V3.1 Terminus measured
DTBench83.2%81.3%Claude Sonnet 4.5
LMCA38.8%28.6%Claude Sonnet 4.5
LMArena Text14381419Claude Sonnet 4.5
LMArena Text: instruction following14591404Claude Sonnet 4.5
LMArena Text: creative writing14421403Claude Sonnet 4.5
LMArena Text: English14501429Claude Sonnet 4.5
LMArena Text: non-English14251408Claude Sonnet 4.5
LMArena Text: Chinese1460Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: German1427Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: Japanese1390Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: Korean1402Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: French1459Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: Spanish1458Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: Russian14371435Claude Sonnet 4.5
LMArena Text: Polish14231427DeepSeek V3.1 Terminus
LMArena Text: multi-turn14651411Claude Sonnet 4.5
LMArena Text: longer queries14751422Claude Sonnet 4.5
LMArena Text: writing and language14421409Claude Sonnet 4.5
LMArena Text: entertainment and media14281391Claude Sonnet 4.5
LMArena Document1450Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 22 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Sonnet 4.5 and DeepSeek V3.1 Terminus
BenchmarkClaude Sonnet 4.5DeepSeek V3.1 TerminusLeader
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 Sonnet 4.5$0.011Fits in one request
DeepSeek V3.1 Terminus$0.0008Fits in one request

DeepSeek V3.1 Terminus costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
DeepSeek V3.1 Terminus$0.018Fits in one request

DeepSeek V3.1 Terminus costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
DeepSeek V3.1 Terminus$0.071Exceeds the context window

DeepSeek V3.1 Terminus 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 Sonnet 4.5 and DeepSeek V3.1 Terminus
SpecificationAnthropic Claude Sonnet 4.5DeepSeek V3.1 Terminus
MakerAnthropicDeepSeek
WeightsNo public weights listedOpen weights
ReleasedSeptember 29, 2025September 22, 2025
Context window1M164K
Input $/Mtok$3.00$0.3063
Output $/Mtok$15.00$1.0142
Coding index39.5Not benchmarked
Independent measurements behind it30
Cost per solved task$1.16Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than DeepSeek V3.1 Terminus for coding?

Only Claude Sonnet 4.5 has a coding score, 39.5 on the Vibe Coding Index; DeepSeek V3.1 Terminus has none, so the two cannot be ranked on coding. Pick DeepSeek V3.1 Terminus for output tokens 14.8x cheaper ($1.0142 vs $15.00 per million) and work measured by LMArena Text: science or LMArena Text: medicine and healthcare, where it leads.

Which is cheaper, Claude Sonnet 4.5 or DeepSeek V3.1 Terminus?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; DeepSeek V3.1 Terminus costs $0.3063 and $1.0142. Cost per solved task is known for Claude Sonnet 4.5 only.

Which has the bigger context window, Claude Sonnet 4.5 or DeepSeek V3.1 Terminus?

Claude Sonnet 4.5, with 1M tokens against 164K.

How many benchmarks is the Claude Sonnet 4.5 vs DeepSeek V3.1 Terminus comparison based on?

33 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and DeepSeek V3.1 Terminus's on 0. Where only one model has a result, the page says so instead of naming a winner.

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