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Claude Opus 4.8 vs GPT-6 Astra

Updated October 21, 2026. 100 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Opus 4.8 Replace GPT-6 Astra
Claude Opus 4.8Anthropic
Coding
66.0
Overall
41.8
Output $/M
$25.00
39
GPT-6 AstraOpenAI
Coding
88.7
Overall
52.7
Output $/M
$50.00
61
vs boards won of 100 shared

Decision reading

Pick GPT-6 Astra for coding: it scores 88.7 on the Vibe Coding Index against 66.0 for Claude Opus 4.8.

Pick Claude Opus 4.8 when output tokens cost 2.0x less, or when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.

Model AClaude Opus 4.8Anthropic66.0/1002 independent benchmarks$2.17 per solved taskModel BGPT-6 AstraOpenAI88.7/1002 independent benchmarksNo cost per solved task
Shared results
100
Claude Opus 4.8 only
26
GPT-6 Astra only
19
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 4.8 66.0 from 2 benchmarks, GPT-6 Astra 88.7 from 2 benchmarks.
Widest category
Agentic work, 20.0 points apart on average over 18 shared benchmarks.
Widest single gap
Time Horizon Index (Vals AI): Claude Opus 4.8 11.8% against GPT-6 Astra 90.5%, 78.7 points apart on a 0 to 100 scale.
Output price
Claude Opus 4.8 $25.00 against GPT-6 Astra $50.00 per million output tokens, 2.0x apart.
Context window
Claude Opus 4.8 takes 1M tokens, GPT-6 Astra 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 4.8BarsGPT-6 AstraTies
Coding214
Intelligence02
Agentic work414
Reasoning410
Math24
Knowledge51
Web design09
General227
All shared boards3961
CodingLike-for-likeFour of these boards feed the Vibe Coding Index214
Coding benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
LiveBench coding77.3%93.7%GPT-6 Astra
LMArena WebDev15561774GPT-6 Astra
AA Coding Index74.376.9GPT-6 Astra
LiveCodeBench (Vals AI)87.8%Not measuredOnly Claude Opus 4.8 measured
SWE-bench Verified (Vals AI)88.6%Not measuredOnly Claude Opus 4.8 measured
Terminal-Bench 4 (Vals AI)23.2%59.6%GPT-6 Astra
Vibe Code Bench (Vals AI)82.7%89.6%GPT-6 Astra
Code migration (Vals AI)47.3%67.7%GPT-6 Astra
ProgramBench (Vals AI)1.0%5.5%GPT-6 Astra
IOI (Vals AI)Not measured100.0%Only GPT-6 Astra measured
Terminal-Bench 2.1 (Vals AI)71.9%87.3%GPT-6 Astra
SWE-bench Multimodal (Vals AI)Not measured43.3%Only GPT-6 Astra measured
Vibe Code Bench 1-100 (Vals AI)Not measured27.6%Only GPT-6 Astra measured
SkillsBench (Vals AI)59.2%Not measuredOnly Claude Opus 4.8 measured
CyberBench (Vals AI)Not measured41.1%Only GPT-6 Astra measured
SciCode54.4%56.5%GPT-6 Astra
Terminal-Bench Hard (Artificial Analysis run)58.3%Not measuredOnly Claude Opus 4.8 measured
FrontierCode46.5%53.3%GPT-6 Astra
FrontierSWENot measured65.5%Only GPT-6 Astra measured
GSO-Bench47.1%79.4%GPT-6 Astra
WeirdML82.9%93.3%GPT-6 Astra
MirrorCodeNot measured46.7%Only GPT-6 Astra measured
ALE-BenchNot measured2951.3Only GPT-6 Astra measured
LMArena Text: coding14901489Claude Opus 4.8
LMArena Text: software and IT14881474Claude Opus 4.8
LMArena WebDev: React15571798GPT-6 Astra
LMArena WebDev: HTML15431775GPT-6 Astra
LMArena WebDev: from an imageNot measured1726Only GPT-6 Astra measured
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
AA Intelligence Index41.852.7GPT-6 Astra
Epoch Capabilities Index159.0168.8GPT-6 Astra
Agentic workLike-for-likePublic boards, shown as published, kept out of the index414
Agentic work benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
AA Agentic Index41.951.0GPT-6 Astra
Design Arena: agents building web apps12331372GPT-6 Astra
Design Arena: agents building full-stack apps12491357GPT-6 Astra
Design Arena: agents building mobile apps12221312GPT-6 Astra
Design Arena: agents building Android apps1237Not measuredOnly Claude Opus 4.8 measured
Design Arena: agents building Godot games12311348GPT-6 Astra
Design Arena: agents building games1238Not measuredOnly Claude Opus 4.8 measured
Design Arena: HTML slides1221Not measuredOnly Claude Opus 4.8 measured
Design Arena: PowerPoint slides12271245GPT-6 Astra
Design Arena: spreadsheetsNot measured1380Only GPT-6 Astra measured
LiveBench research81.8%85.2%GPT-6 Astra
LiveBench browser96.0%84.0%Claude Opus 4.8
LiveBench long agentic48.3%82.4%GPT-6 Astra
SREBench (Vals AI)Not measured56.9%Only GPT-6 Astra measured
Finance Agent (Vals AI)53.9%53.5%Claude Opus 4.8
Tax Agent Bench (Vals AI)30.0%20.7%Claude Opus 4.8
Legal Research Bench (Vals AI)43.8%39.4%Claude Opus 4.8
Harvey's Legal Agent Benchmark (Vals AI)Not measured7.1%Only GPT-6 Astra measured
Excel Modeling Benchmark (Vals AI)69.4%71.7%GPT-6 Astra
BioMysteryBench (Vals AI)Not measured79.3%Only GPT-6 Astra measured
Terminal-Bench-Science (Vals AI)4.3%62.9%GPT-6 Astra
Vals Science IndexNot measured65.1%Only GPT-6 Astra measured
Time Horizon Index (Vals AI)11.8%90.5%GPT-6 Astra
CUA-bench (Vals AI)Not measured19.2%Only GPT-6 Astra measured
Robo-bench (Vals AI)Not measured23.3%Only GPT-6 Astra measured
τ²-Bench Telecom94.4%Not measuredOnly Claude Opus 4.8 measured
APEX-Agents48.9%64.7%GPT-6 Astra
Remote Labor Index8.3%20.8%GPT-6 Astra
OSWorld 2.020.6%Not measuredOnly Claude Opus 4.8 measured
BALROGNot measured68.3%Only GPT-6 Astra measured
DeepResearch Bench50.2%Not measuredOnly Claude Opus 4.8 measured
PostTrainBench33.8%Not measuredOnly Claude Opus 4.8 measured
SpireClimbNot measured25.7%Only GPT-6 Astra measured
Vending-Bench 2$5,787$15,515GPT-6 Astra
LMArena Search1204Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 4 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index410
Reasoning benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
GPQA Diamond92.4%Not measuredOnly Claude Opus 4.8 measured
LiveBench reasoning89.2%92.7%GPT-6 Astra
MysteryMechanism (Vals AI)Not measured53.1%Only GPT-6 Astra measured
MMMU Pro (Vals AI)86.6%Not measuredOnly Claude Opus 4.8 measured
GPQA Diamond (Artificial Analysis run)92.0%96.3%GPT-6 Astra
Humanity's Last Exam (Artificial Analysis run)48.7%54.7%GPT-6 Astra
GPQA Diamond (Epoch AI run)91.0%95.8%GPT-6 Astra
ARC-AGI92.5%98.5%GPT-6 Astra
ARC-AGI-272.1%95.0%GPT-6 Astra
SimpleBench64.8%Not measuredOnly Claude Opus 4.8 measured
Chess puzzles52.0%74.0%GPT-6 Astra
Mystery game puzzles36.0%84.0%GPT-6 Astra
EBR-bench28.6%76.2%GPT-6 Astra
LMArena Text: hard prompts14821463Claude Opus 4.8
LMArena Text: expert15031489Claude Opus 4.8
LMArena Text: hard prompts in English14871464Claude Opus 4.8
LMArena Vision: diagrams13151297Claude Opus 4.8
LMArena Vision: homework13371337GPT-6 Astra
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index24
Math benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
OTIS Mock AIME98.3%100.0%GPT-6 Astra
FrontierMath, tiers 1 to 380.0%93.7%GPT-6 Astra
FrontierMath, tier 456.1%97.6%GPT-6 Astra
ProofBench69.0%99.0%GPT-6 Astra
LMArena Text: math14861465Claude Opus 4.8
LMArena Text: mathematical work14971484Claude Opus 4.8
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index51
Knowledge benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
MMLU Pro89.6%Not measuredOnly Claude Opus 4.8 measured
LegalBench (Vals AI)83.6%Not measuredOnly Claude Opus 4.8 measured
CorpFin (Vals AI)66.7%Not measuredOnly Claude Opus 4.8 measured
TaxEval (Vals AI)75.6%Not measuredOnly Claude Opus 4.8 measured
MortgageTax (Vals AI)69.9%Not measuredOnly Claude Opus 4.8 measured
MedCode (Vals AI)53.2%48.5%Claude Opus 4.8
SimpleQA Verified53.0%75.6%GPT-6 Astra
LMArena Text: science14771451Claude Opus 4.8
LMArena Text: medicine and healthcare14641425Claude Opus 4.8
LMArena Text: legal and government14771462Claude Opus 4.8
LMArena Text: business and finance14581439Claude Opus 4.8
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index09
Web design benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
Design Arena: websites12581337GPT-6 Astra
Design Arena: UI components12561394GPT-6 Astra
Design Arena: game dev12641474GPT-6 Astra
Design Arena: data viz12401335GPT-6 Astra
Design Arena: 3D12231501GPT-6 Astra
Design Arena: all code categories12551379GPT-6 Astra
Design Arena: SVG11941431GPT-6 Astra
Design Arena: ASCII art12761359GPT-6 Astra
LiveBench design78.8%82.0%GPT-6 Astra
GeneralLike-for-likePublic boards, shown as published, kept out of the index227
General benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
Vals IndexNot measured65.0%Only GPT-6 Astra measured
LiveBench data analysis66.0%83.0%GPT-6 Astra
Public Benefits Bench (Vals AI)68.1%Not measuredOnly Claude Opus 4.8 measured
SAGE (Vals AI)54.8%46.4%Claude Opus 4.8
MedScribe (Vals AI)85.8%87.9%GPT-6 Astra
Vals Multimodal Index70.9%Not measuredOnly Claude Opus 4.8 measured
IFBench62.2%Not measuredOnly Claude Opus 4.8 measured
Long context reasoning (AA-LCR)77.7%80.7%GPT-6 Astra
DTBench94.9%97.3%GPT-6 Astra
LMCA57.5%64.4%GPT-6 Astra
Surface Evolver Bench87.5%Not measuredOnly Claude Opus 4.8 measured
Furniture assembly42.5%80.0%GPT-6 Astra
LMArena Text14611441Claude Opus 4.8
LMArena Text: instruction following14761455Claude Opus 4.8
LMArena Text: creative writing14541420Claude Opus 4.8
LMArena Vision12941280Claude Opus 4.8
LMArena Text: English14681447Claude Opus 4.8
LMArena Text: non-English14501432Claude Opus 4.8
LMArena Text: Chinese15061489Claude Opus 4.8
LMArena Text: German14721459Claude Opus 4.8
LMArena Text: Japanese14421405Claude Opus 4.8
LMArena Text: Korean14311428Claude Opus 4.8
LMArena Text: French14811432Claude Opus 4.8
LMArena Text: Spanish14651422Claude Opus 4.8
LMArena Text: Russian14741438Claude Opus 4.8
LMArena Text: Polish14591422Claude Opus 4.8
LMArena Text: multi-turn14761447Claude Opus 4.8
LMArena Text: longer queries14831460Claude Opus 4.8
LMArena Text: writing and language14611437Claude Opus 4.8
LMArena Text: entertainment and media14401427Claude Opus 4.8
LMArena Vision: English12931280Claude Opus 4.8
LMArena Vision: Chinese13461361GPT-6 Astra
LMArena Vision: reading text13031292Claude Opus 4.8
LMArena Vision: humor1282Not measuredOnly Claude Opus 4.8 measured
LMArena Vision: creative writing13011286Claude Opus 4.8
LMArena Document1475Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 4.8 and GPT-6 Astra
BenchmarkClaude Opus 4.8GPT-6 AstraLeader
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 4.8$0.018Fits in one request
GPT-6 Astra$0.035Fits in one request

Claude Opus 4.8 costs less

Repository review

50K input + 3K output tokens

Claude Opus 4.8$0.325Fits in one request
GPT-6 Astra$0.650Fits in one request

Claude Opus 4.8 costs less

Agent loop

200K input + 10K output tokens

Claude Opus 4.8$1.25Fits in one request
GPT-6 Astra$2.50Fits in one request

Claude Opus 4.8 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 4.8 and GPT-6 Astra
SpecificationAnthropic Claude Opus 4.8OpenAI GPT-6 Astra
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMay 27, 2026September 4, 2026
Context window1M1.05M
Input $/Mtok$5.00$10.00
Output $/Mtok$25.00$50.00
Coding index66.088.7
Independent measurements behind it22
Cost per solved task$2.17Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 4.8 better than GPT-6 Astra for coding?

Pick GPT-6 Astra for coding: it scores 88.7 on the Vibe Coding Index against 66.0 for Claude Opus 4.8. Pick Claude Opus 4.8 when output tokens cost 2.0x less, or when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.

Which is cheaper, Claude Opus 4.8 or GPT-6 Astra?

Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens; GPT-6 Astra costs $10.00 and $50.00. Cost per solved task is known for Claude Opus 4.8 only.

Which has the bigger context window, Claude Opus 4.8 or GPT-6 Astra?

GPT-6 Astra, with 1.05M tokens against 1M.

How many benchmarks is the Claude Opus 4.8 vs GPT-6 Astra comparison based on?

100 benchmarks have a result for both models as of October 21, 2026. Claude Opus 4.8's coding index rests on 2 independent benchmarks and GPT-6 Astra's on 2. Where only one model has a result, the page says so instead of naming a winner.

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