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GPT-5.6 Sol vs GPT-6 Astra

GPT-6 Astra leads GPT-5.6 Sol on coding, 85.1 to 73.5 on the Vibe Coding Index, and GPT-5.6 Sol costs 2.5x less per output token ($20.00 vs $50.00 per million). Updated October 22, 2026; 113 benchmarks have a result for both.

Replace GPT-5.6 Sol Replace GPT-6 Astra
GPT-5.6 SolOpenAI
Coding
73.5
Overall
74.7
Output $/M
$20.00
41
GPT-6 AstraOpenAI
Coding
85.1
Overall
83.0
Output $/M
$50.00
71
vs boards won of 113 shared, 1 tied

GPT-5.6 Sol or GPT-6 Astra: which to pick

Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 73.5 for GPT-5.6 Sol, though on 5 benchmarks against 6.

Pick GPT-5.6 Sol for output tokens 2.5x cheaper ($20.00 vs $50.00 per million) and work measured by AA Coding Index or CyberBench (Vals AI), where it leads.

Model AGPT-5.6 SolOpenAI73.5/1006 independent benchmarks$1.20 per solved taskModel BGPT-6 AstraOpenAI85.1/1005 independent benchmarksNo cost per solved task
Shared results
113
GPT-5.6 Sol only
26
GPT-6 Astra only
8
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
GPT-5.6 Sol 73.5 from 6 benchmarks, GPT-6 Astra 85.1 from 5 benchmarks.
Widest category
Agentic work, 17.2 points apart on average over 21 shared benchmarks.
Widest single gap
Time Horizon Index (Vals AI): GPT-5.6 Sol 23.8% against GPT-6 Astra 90.5%, 66.7 points apart on a 0 to 100 scale.
Output price
GPT-5.6 Sol $20.00 against GPT-6 Astra $50.00 per million output tokens, 2.5x apart.
Context window
Both take 1.05M tokens.

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
CategoryGPT-5.6 SolBarsGPT-6 AstraTies
Coding519
Intelligence02
Agentic work516
Reasoning411
Math231 tie
Knowledge43
Web design09
General218
All shared boards41711 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index519
Coding benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
LiveBench coding89.7%93.7%GPT-6 Astra
LMArena WebDev16161774GPT-6 Astra
AA Coding Index77.476.9GPT-5.6 Sol
LiveCodeBench (Vals AI)82.6%Not measuredOnly GPT-5.6 Sol measured
SWE-bench Verified (Vals AI)96.2%Not measuredOnly GPT-5.6 Sol measured
Terminal-Bench 4 (Vals AI)37.9%59.6%GPT-6 Astra
Vibe Code Bench (Vals AI)80.5%89.6%GPT-6 Astra
Code migration (Vals AI)52.9%67.7%GPT-6 Astra
ProgramBench (Vals AI)1.5%5.5%GPT-6 Astra
IOI (Vals AI)91.2%100.0%GPT-6 Astra
Terminal-Bench 2.1 (Vals AI)85.8%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)20.0%27.6%GPT-6 Astra
SkillsBench (Vals AI)54.1%Not measuredOnly GPT-5.6 Sol measured
CyberBench (Vals AI)76.3%41.1%GPT-5.6 Sol
SciCode57.8%56.5%GPT-5.6 Sol
Terminal-Bench Hard (Artificial Analysis run)65.9%Not measuredOnly GPT-5.6 Sol measured
FrontierCode47.5%53.3%GPT-6 Astra
FrontierSWE32.2%65.5%GPT-6 Astra
GSO-Bench76.5%79.4%GPT-6 Astra
WeirdML88.8%93.3%GPT-6 Astra
MirrorCode20.0%46.7%GPT-6 Astra
ALE-Bench2176.92951.3GPT-6 Astra
LMArena Text: coding14961489GPT-5.6 Sol
LMArena Text: software and IT14891474GPT-5.6 Sol
LMArena WebDev: React16201798GPT-6 Astra
LMArena WebDev: HTML16181775GPT-6 Astra
LMArena WebDev: from an image16091726GPT-6 Astra
SciCode10.8%12.3%GPT-6 Astra
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 GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
AA Intelligence Index47.052.7GPT-6 Astra
Epoch Capabilities Index162.8168.8GPT-6 Astra
Agentic workLike-for-likePublic boards, shown as published, kept out of the index516
Agentic work benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
AA Agentic Index50.251.0GPT-6 Astra
Design Arena: agents building web apps12451374GPT-6 Astra
Design Arena: agents building full-stack apps12611357GPT-6 Astra
Design Arena: agents building mobile apps12481312GPT-6 Astra
Design Arena: agents building Android apps1240Not measuredOnly GPT-5.6 Sol measured
Design Arena: agents building Godot games12601348GPT-6 Astra
Design Arena: agents building games1266Not measuredOnly GPT-5.6 Sol measured
Design Arena: HTML slides1236Not measuredOnly GPT-5.6 Sol measured
Design Arena: PowerPoint slides12171219GPT-6 Astra
Design Arena: spreadsheetsNot measured1379Only GPT-6 Astra measured
LiveBench research54.5%85.2%GPT-6 Astra
LiveBench browser88.0%84.0%GPT-5.6 Sol
LiveBench long agentic48.5%82.4%GPT-6 Astra
SREBench (Vals AI)30.5%56.9%GPT-6 Astra
Finance Agent (Vals AI)53.8%53.5%GPT-5.6 Sol
Tax Agent Bench (Vals AI)31.1%20.7%GPT-5.6 Sol
Legal Research Bench (Vals AI)48.1%39.4%GPT-5.6 Sol
Harvey's Legal Agent Benchmark (Vals AI)Not measured7.1%Only GPT-6 Astra measured
Excel Modeling Benchmark (Vals AI)72.3%71.7%GPT-5.6 Sol
BioMysteryBench (Vals AI)71.1%79.3%GPT-6 Astra
Terminal-Bench-Science (Vals AI)20.0%62.9%GPT-6 Astra
Vals Science Index41.5%65.1%GPT-6 Astra
Time Horizon Index (Vals AI)23.8%90.5%GPT-6 Astra
CUA-bench (Vals AI)8.3%19.2%GPT-6 Astra
Robo-bench (Vals AI)Not measured23.3%Only GPT-6 Astra measured
τ²-Bench Telecom85.1%Not measuredOnly GPT-5.6 Sol measured
APEX-AgentsNot measured64.7%Only GPT-6 Astra measured
Remote Labor IndexNot measured20.8%Only GPT-6 Astra measured
OSWorld 2.027.3%Not measuredOnly GPT-5.6 Sol measured
BALROG60.0%68.3%GPT-6 Astra
PostTrainBench36.2%Not measuredOnly GPT-5.6 Sol measured
SpireClimbNot measured25.7%Only GPT-6 Astra measured
Vending-Bench 2$9,619$15,515GPT-6 Astra
LMArena Search1261Not measuredOnly GPT-5.6 Sol measured
Neither model has a result on the other 7 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index411
Reasoning benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
GPQA Diamond95.2%Not measuredOnly GPT-5.6 Sol measured
LiveBench reasoning91.7%92.7%GPT-6 Astra
MysteryMechanism (Vals AI)33.3%53.1%GPT-6 Astra
MMMU Pro (Vals AI)88.8%Not measuredOnly GPT-5.6 Sol measured
GPQA Diamond (Artificial Analysis run)94.1%96.3%GPT-6 Astra
Humanity's Last Exam (Artificial Analysis run)49.5%54.7%GPT-6 Astra
GPQA Diamond (Epoch AI run)93.5%95.8%GPT-6 Astra
ARC-AGI97.5%98.5%GPT-6 Astra
ARC-AGI-292.5%95.0%GPT-6 Astra
SimpleBench64.8%Not measuredOnly GPT-5.6 Sol measured
Chess puzzles59.0%74.0%GPT-6 Astra
Mystery game puzzles58.0%84.0%GPT-6 Astra
EBR-bench44.8%76.2%GPT-6 Astra
LMArena Text: hard prompts14831463GPT-5.6 Sol
LMArena Text: expert15171489GPT-5.6 Sol
LMArena Text: hard prompts in English14771464GPT-5.6 Sol
LMArena Vision: diagrams13051297GPT-5.6 Sol
LMArena Vision: homework13051337GPT-6 Astra
Kagi LLM Benchmark67.0%Not measuredOnly GPT-5.6 Sol measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index23
Math benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
OTIS Mock AIME100.0%100.0%Tie
FrontierMath, tiers 1 to 389.1%93.7%GPT-6 Astra
FrontierMath, tier 482.9%97.6%GPT-6 Astra
ProofBench83.0%99.0%GPT-6 Astra
LMArena Text: math14731465GPT-5.6 Sol
LMArena Text: mathematical work14961484GPT-5.6 Sol
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index43
Knowledge benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
MMLU Pro89.1%Not measuredOnly GPT-5.6 Sol measured
LegalBench (Vals AI)87.0%Not measuredOnly GPT-5.6 Sol measured
CorpFin (Vals AI)64.4%Not measuredOnly GPT-5.6 Sol measured
TaxEval (Vals AI)74.8%Not measuredOnly GPT-5.6 Sol measured
MortgageTax (Vals AI)67.3%Not measuredOnly GPT-5.6 Sol measured
MedCode (Vals AI)44.0%48.5%GPT-6 Astra
SimpleQA Verified69.7%75.6%GPT-6 Astra
LMArena Text: science14551451GPT-5.6 Sol
LMArena Text: medicine and healthcare14311425GPT-5.6 Sol
LMArena Text: legal and government14761462GPT-5.6 Sol
LMArena Text: business and finance14571439GPT-5.6 Sol
FACTS Benchmark Suite52.4%75.7%GPT-6 Astra
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 GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
Design Arena: websites13211336GPT-6 Astra
Design Arena: UI components13351394GPT-6 Astra
Design Arena: game dev13671479GPT-6 Astra
Design Arena: data viz13231334GPT-6 Astra
Design Arena: 3D13841500GPT-6 Astra
Design Arena: all code categories13411378GPT-6 Astra
Design Arena: SVG13151430GPT-6 Astra
Design Arena: ASCII art13041353GPT-6 Astra
LiveBench design81.6%82.0%GPT-6 Astra
GeneralLike-for-likePublic boards, shown as published, kept out of the index218
General benchmarks for GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-6 AstraLeader
Vals IndexNot measured65.0%Only GPT-6 Astra measured
LiveBench data analysis79.8%83.0%GPT-6 Astra
Public Benefits Bench (Vals AI)66.5%Not measuredOnly GPT-5.6 Sol measured
SAGE (Vals AI)52.6%46.4%GPT-5.6 Sol
MedScribe (Vals AI)85.2%87.9%GPT-6 Astra
Vals Multimodal Index72.6%Not measuredOnly GPT-5.6 Sol measured
IFBench72.7%Not measuredOnly GPT-5.6 Sol measured
Long context reasoning (AA-LCR)84.0%80.7%GPT-5.6 Sol
DTBench95.7%97.3%GPT-6 Astra
LMCA58.5%64.4%GPT-6 Astra
Surface Evolver Bench93.1%Not measuredOnly GPT-5.6 Sol measured
Furniture assembly56.7%80.0%GPT-6 Astra
LMArena Text14571441GPT-5.6 Sol
LMArena Text: instruction following14831455GPT-5.6 Sol
LMArena Text: creative writing14491420GPT-5.6 Sol
LMArena Vision12811280GPT-5.6 Sol
LMArena Text: English14571447GPT-5.6 Sol
LMArena Text: non-English14511432GPT-5.6 Sol
LMArena Text: Chinese15251489GPT-5.6 Sol
LMArena Text: German14761459GPT-5.6 Sol
LMArena Text: Japanese14721405GPT-5.6 Sol
LMArena Text: Korean14421428GPT-5.6 Sol
LMArena Text: French14721432GPT-5.6 Sol
LMArena Text: Spanish14431422GPT-5.6 Sol
LMArena Text: Russian14711438GPT-5.6 Sol
LMArena Text: Polish14591422GPT-5.6 Sol
LMArena Text: multi-turn14611447GPT-5.6 Sol
LMArena Text: longer queries14811460GPT-5.6 Sol
LMArena Text: writing and language14621437GPT-5.6 Sol
LMArena Text: entertainment and media14501427GPT-5.6 Sol
LMArena Vision: English12801280GPT-5.6 Sol
LMArena Vision: Chinese13131361GPT-6 Astra
LMArena Vision: reading text12901292GPT-6 Astra
LMArena Vision: humor1246Not measuredOnly GPT-5.6 Sol measured
LMArena Vision: creative writing12831286GPT-6 Astra
LMArena Document1483Not measuredOnly GPT-5.6 Sol 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 GPT-5.6 Sol and GPT-6 Astra
BenchmarkGPT-5.6 SolGPT-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

GPT-5.6 Sol$0.014Fits in one request
GPT-6 Astra$0.035Fits in one request

GPT-5.6 Sol costs less

Repository review

50K input + 3K output tokens

GPT-5.6 Sol$0.260Fits in one request
GPT-6 Astra$0.650Fits in one request

GPT-5.6 Sol costs less

Agent loop

200K input + 10K output tokens

GPT-5.6 Sol$1.00Fits in one request
GPT-6 Astra$2.50Fits in one request

GPT-5.6 Sol 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 GPT-5.6 Sol and GPT-6 Astra
SpecificationOpenAI GPT-5.6 SolOpenAI GPT-6 Astra
MakerOpenAIOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJuly 9, 2026September 4, 2026
Context window1.05M1.05M
Input $/Mtok$4.00$10.00
Output $/Mtok$20.00$50.00
Coding index73.585.1
Independent measurements behind it65
Cost per solved task$1.20Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.6 Sol better than GPT-6 Astra for coding?

Pick GPT-6 Astra for coding: it scores 85.1 on the Vibe Coding Index against 73.5 for GPT-5.6 Sol, though on 5 benchmarks against 6. Pick GPT-5.6 Sol for output tokens 2.5x cheaper ($20.00 vs $50.00 per million) and work measured by AA Coding Index or CyberBench (Vals AI), where it leads.

Which is cheaper, GPT-5.6 Sol or GPT-6 Astra?

GPT-5.6 Sol costs $4.00 per million input tokens and $20.00 per million output tokens; GPT-6 Astra costs $10.00 and $50.00. Cost per solved task is known for GPT-5.6 Sol only.

Which has the bigger context window, GPT-5.6 Sol or GPT-6 Astra?

Neither: both take 1.05M tokens.

How many benchmarks is the GPT-5.6 Sol vs GPT-6 Astra comparison based on?

113 benchmarks have a result for both models as of October 22, 2026. GPT-5.6 Sol's coding index rests on 6 independent benchmarks and GPT-6 Astra's on 5. Where only one model has a result, the page says so instead of naming a winner.

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