GPT-5.6 Terra vs Muse Spark Open

GPT-5.6 Terra leads Muse Spark Open on coding, 63.9 to 47.4 on the Vibe Coding Index, and Muse Spark Open costs 2.8x less per output token ($4.25 vs $12.00 per million). Updated October 22, 2026; 26 benchmarks have a result for both.

Replace GPT-5.6 Terra Replace Muse Spark Open

GPT-5.6 TerraOpenAI

Coding: 63.9
Overall: 68.1
Output $/M: $12.00

Muse Spark OpenMeta

Coding: 47.4
Overall: 44.9
Output $/M: $4.25

vs boards won of 26 shared

GPT-5.6 Terra or Muse Spark Open: which to pick

Pick GPT-5.6 Terra for coding: it scores 63.9 on the Vibe Coding Index against 47.4 for Muse Spark Open.

Pick Muse Spark Open for output tokens 2.8x cheaper ($4.25 vs $12.00 per million) and work measured by LMArena WebDev or Vibe Code Bench (Vals AI), where it leads.

Model AGPT-5.6 TerraOpenAI63.9/1006 independent benchmarks$0.42 per solved task Model BMuse Spark OpenMeta47.4/1004 independent benchmarksNo cost per solved task

261012

Shared results: 26
GPT-5.6 Terra only: 101
Muse Spark Open only: 2
Like-for-like categories: 6 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.

Coding
Vibe Coding Index, six public coding benchmarks
GPT-5.6 Terra
GPT-5.6 Terra scores 63.9 against 47.4.
6 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only GPT-5.6 Terra has a AA Intelligence Index result, 42.1.
Directional only
Agentic work
AA Agentic Index
No call
Only GPT-5.6 Terra has a AA Agentic Index result, 43.2.
Directional only
Reasoning
GPQA Diamond
No call
Only GPT-5.6 Terra has a GPQA Diamond result, 90.9%.
Directional only
Knowledge
MMLU Pro
No call
Only GPT-5.6 Terra has a MMLU Pro result, 86.7%.
Directional only
Web design
Design Arena: websites
Muse Spark Open
Muse Spark Open leads, 1310 against 1268.
Same board, both measured
General
Vals Index
No call
Only Muse Spark Open has a Vals Index result, 48.6%.
Directional only
Long documents
Listed context window
GPT-5.6 Terra
GPT-5.6 Terra takes 1.05M tokens against 1.05M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Spark Open
GPT-5.6 Terra $0.0080, Muse Spark Open $0.0034 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.6 Terra has the number, $0.42.
Directional only

At a glance

Coding index: GPT-5.6 Terra 63.9 from 6 benchmarks, Muse Spark Open 47.4 from 4 benchmarks.
Widest category: Agentic work, 18.5 points apart on average over 8 shared benchmarks.
Widest single gap: LiveBench browser: GPT-5.6 Terra 84.0% against Muse Spark Open 36.0%, 48.0 points apart on a 0 to 100 scale.
Output price: GPT-5.6 Terra $12.00 against Muse Spark Open $4.25 per million output tokens, 2.8x apart.
Context window: GPT-5.6 Terra takes 1.05M tokens, Muse Spark Open 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
Category	GPT-5.6 Terra	Muse Spark Open
Coding	5	4
Intelligence	1	0
Agentic work	6	2
Reasoning	2	1
Web design	1	2
General	2	0
All shared boards	17	9

CodingLike-for-likeSix of these boards feed the Vibe Coding Index54

Coding benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
LiveBench coding	86.2%	73.6%	GPT-5.6 Terra
LMArena WebDev	1522	1528	Muse Spark Open
AA Coding Index	76.7	Not measured	Only GPT-5.6 Terra measured
LiveCodeBench (Vals AI)	85.9%	Not measured	Only GPT-5.6 Terra measured
SWE-bench Verified (Vals AI)	95.4%	Not measured	Only GPT-5.6 Terra measured
Terminal-Bench 4 (Vals AI)	22.7%	6.6%	GPT-5.6 Terra
Vibe Code Bench (Vals AI)	74.6%	76.2%	Muse Spark Open
Code migration (Vals AI)	47.8%	21.2%	GPT-5.6 Terra
ProgramBench (Vals AI)	0.5%	Not measured	Only GPT-5.6 Terra measured
IOI (Vals AI)	87.6%	Not measured	Only GPT-5.6 Terra measured
Terminal-Bench 2.1 (Vals AI)	77.5%	Not measured	Only GPT-5.6 Terra measured
Vibe Code Bench 1-100 (Vals AI)	14.8%	Not measured	Only GPT-5.6 Terra measured
SkillsBench (Vals AI)	58.9%	Not measured	Only GPT-5.6 Terra measured
CyberBench (Vals AI)	72.1%	Not measured	Only GPT-5.6 Terra measured
SciCode	55.0%	58.4%	Muse Spark Open
Terminal-Bench Hard (Artificial Analysis run)	62.9%	Not measured	Only GPT-5.6 Terra measured
FrontierCode	41.3%	Not measured	Only GPT-5.6 Terra measured
WeirdML	78.3%	Not measured	Only GPT-5.6 Terra measured
ALE-Bench	1951.4	1590.1	GPT-5.6 Terra
LMArena Text: coding	1485	Not measured	Only GPT-5.6 Terra measured
LMArena Text: software and IT	1482	Not measured	Only GPT-5.6 Terra measured
LMArena WebDev: React	1513	1529	Muse Spark Open
LMArena WebDev: HTML	1526	1495	GPT-5.6 Terra
LMArena WebDev: from an image	1541	Not measured	Only GPT-5.6 Terra measured
SciCode	10.8%	Not measured	Only GPT-5.6 Terra measured
Neither model has a result on the other 14 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10

Intelligence benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
AA Intelligence Index	42.1	Not measured	Only GPT-5.6 Terra measured
Epoch Capabilities Index	160.1	155.1	GPT-5.6 Terra

Agentic workLike-for-likePublic boards, shown as published, kept out of the index62

Agentic work benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
AA Agentic Index	43.2	Not measured	Only GPT-5.6 Terra measured
Design Arena: agents building web apps	1120	Not measured	Only GPT-5.6 Terra measured
Design Arena: agents building full-stack apps	1061	Not measured	Only GPT-5.6 Terra measured
Design Arena: agents building mobile apps	1111	Not measured	Only GPT-5.6 Terra measured
Design Arena: agents building Android apps	1062	Not measured	Only GPT-5.6 Terra measured
Design Arena: agents building games	1083	Not measured	Only GPT-5.6 Terra measured
Design Arena: HTML slides	1058	Not measured	Only GPT-5.6 Terra measured
Design Arena: PowerPoint slides	1105	Not measured	Only GPT-5.6 Terra measured
LiveBench research	60.4%	80.3%	Muse Spark Open
LiveBench browser	84.0%	36.0%	GPT-5.6 Terra
LiveBench long agentic	48.4%	18.9%	GPT-5.6 Terra
SREBench (Vals AI)	9.5%	Not measured	Only GPT-5.6 Terra measured
Finance Agent (Vals AI)	54.4%	61.3%	Muse Spark Open
Tax Agent Bench (Vals AI)	30.0%	26.3%	GPT-5.6 Terra
Legal Research Bench (Vals AI)	41.4%	38.5%	GPT-5.6 Terra
Harvey's Legal Agent Benchmark (Vals AI)	Not measured	25.0%	Only Muse Spark Open measured
Excel Modeling Benchmark (Vals AI)	66.2%	53.7%	GPT-5.6 Terra
Terminal-Bench-Science (Vals AI)	10.0%	Not measured	Only GPT-5.6 Terra measured
τ²-Bench Telecom	86.3%	Not measured	Only GPT-5.6 Terra measured
APEX-Agents	58.2%	33.4%	GPT-5.6 Terra
BALROG	53.2%	Not measured	Only GPT-5.6 Terra measured
Vending-Bench 2	$7,343	Not measured	Only GPT-5.6 Terra measured
Neither model has a result on the other 19 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index21

Reasoning benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
GPQA Diamond	90.9%	Not measured	Only GPT-5.6 Terra measured
LiveBench reasoning	90.6%	73.7%	GPT-5.6 Terra
MMMU Pro (Vals AI)	86.5%	Not measured	Only GPT-5.6 Terra measured
GPQA Diamond (Artificial Analysis run)	92.5%	89.0%	GPT-5.6 Terra
Humanity's Last Exam (Artificial Analysis run)	42.9%	43.9%	Muse Spark Open
GPQA Diamond (Epoch AI run)	93.3%	Not measured	Only GPT-5.6 Terra measured
ARC-AGI	96.5%	Not measured	Only GPT-5.6 Terra measured
ARC-AGI-2	83.9%	Not measured	Only GPT-5.6 Terra measured
SimpleBench	48.9%	Not measured	Only GPT-5.6 Terra measured
Chess puzzles	47.0%	Not measured	Only GPT-5.6 Terra measured
Mystery game puzzles	35.0%	Not measured	Only GPT-5.6 Terra measured
LMArena Text: hard prompts	1469	Not measured	Only GPT-5.6 Terra measured
LMArena Text: expert	1496	Not measured	Only GPT-5.6 Terra measured
LMArena Text: hard prompts in English	1465	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: diagrams	1295	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: homework	1312	Not measured	Only GPT-5.6 Terra measured
Kagi LLM Benchmark	51.3%	Not measured	Only GPT-5.6 Terra measured
Neither model has a result on the other 5 boards here

MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared

Math benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
OTIS Mock AIME	99.7%	Not measured	Only GPT-5.6 Terra measured
FrontierMath, tiers 1 to 3	86.0%	Not measured	Only GPT-5.6 Terra measured
FrontierMath, tier 4	70.7%	Not measured	Only GPT-5.6 Terra measured
ProofBench	74.0%	Not measured	Only GPT-5.6 Terra measured
LMArena Text: math	1465	Not measured	Only GPT-5.6 Terra measured
LMArena Text: mathematical work	1478	Not measured	Only GPT-5.6 Terra measured
Neither model has a result on the other 7 boards here

KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared

Knowledge benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
MMLU Pro	86.7%	Not measured	Only GPT-5.6 Terra measured
LegalBench (Vals AI)	85.1%	Not measured	Only GPT-5.6 Terra measured
CorpFin (Vals AI)	65.3%	Not measured	Only GPT-5.6 Terra measured
TaxEval (Vals AI)	76.2%	Not measured	Only GPT-5.6 Terra measured
MortgageTax (Vals AI)	67.3%	Not measured	Only GPT-5.6 Terra measured
MedCode (Vals AI)	43.4%	Not measured	Only GPT-5.6 Terra measured
SimpleQA Verified	43.2%	Not measured	Only GPT-5.6 Terra measured
LMArena Text: science	1452	Not measured	Only GPT-5.6 Terra measured
LMArena Text: medicine and healthcare	1430	Not measured	Only GPT-5.6 Terra measured
LMArena Text: legal and government	1461	Not measured	Only GPT-5.6 Terra measured
LMArena Text: business and finance	1448	Not measured	Only GPT-5.6 Terra measured
FACTS Benchmark Suite	52.0%	Not measured	Only GPT-5.6 Terra measured
Neither model has a result on the other 6 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index12

Web design benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
Design Arena: websites	1268	1310	Muse Spark Open
Design Arena: UI components	1256	Not measured	Only GPT-5.6 Terra measured
Design Arena: game dev	1229	1282	Muse Spark Open
Design Arena: data viz	1240	Not measured	Only GPT-5.6 Terra measured
Design Arena: 3D	1134	Not measured	Only GPT-5.6 Terra measured
Design Arena: all code categories	1241	Not measured	Only GPT-5.6 Terra measured
Design Arena: SVG	1219	Not measured	Only GPT-5.6 Terra measured
Design Arena: ASCII art	1177	Not measured	Only GPT-5.6 Terra measured
LiveBench design	76.0%	60.3%	GPT-5.6 Terra

GeneralLike-for-likePublic boards, shown as published, kept out of the index20

General benchmarks for GPT-5.6 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
Vals Index	Not measured	48.6%	Only Muse Spark Open measured
LiveBench data analysis	79.3%	60.2%	GPT-5.6 Terra
Public Benefits Bench (Vals AI)	62.4%	Not measured	Only GPT-5.6 Terra measured
SAGE (Vals AI)	47.0%	Not measured	Only GPT-5.6 Terra measured
MedScribe (Vals AI)	82.9%	Not measured	Only GPT-5.6 Terra measured
Vals Multimodal Index	65.1%	Not measured	Only GPT-5.6 Terra measured
IFBench	71.2%	Not measured	Only GPT-5.6 Terra measured
Long context reasoning (AA-LCR)	83.0%	78.3%	GPT-5.6 Terra
DTBench	93.3%	Not measured	Only GPT-5.6 Terra measured
LMCA	54.9%	Not measured	Only GPT-5.6 Terra measured
Surface Evolver Bench	83.8%	Not measured	Only GPT-5.6 Terra measured
Furniture assembly	54.2%	Not measured	Only GPT-5.6 Terra measured
LMArena Text	1448	Not measured	Only GPT-5.6 Terra measured
LMArena Text: instruction following	1456	Not measured	Only GPT-5.6 Terra measured
LMArena Text: creative writing	1413	Not measured	Only GPT-5.6 Terra measured
LMArena Vision	1271	Not measured	Only GPT-5.6 Terra measured
LMArena Text: English	1449	Not measured	Only GPT-5.6 Terra measured
LMArena Text: non-English	1441	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Chinese	1514	Not measured	Only GPT-5.6 Terra measured
LMArena Text: German	1460	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Japanese	1454	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Korean	1427	Not measured	Only GPT-5.6 Terra measured
LMArena Text: French	1466	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Spanish	1451	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Russian	1452	Not measured	Only GPT-5.6 Terra measured
LMArena Text: Polish	1446	Not measured	Only GPT-5.6 Terra measured
LMArena Text: multi-turn	1453	Not measured	Only GPT-5.6 Terra measured
LMArena Text: longer queries	1454	Not measured	Only GPT-5.6 Terra measured
LMArena Text: writing and language	1431	Not measured	Only GPT-5.6 Terra measured
LMArena Text: entertainment and media	1418	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: English	1272	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: Chinese	1337	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: reading text	1278	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: humor	1236	Not measured	Only GPT-5.6 Terra measured
LMArena Vision: creative writing	1248	Not measured	Only GPT-5.6 Terra measured
LMArena Document	1472	Not measured	Only GPT-5.6 Terra 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 Terra and Muse Spark Open
Benchmark	GPT-5.6 Terra	Muse Spark Open	Leader
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 Terra$0.0080Fits in one request

Muse Spark Open$0.0034Fits in one request

Muse Spark Open costs less

Repository review

50K input + 3K output tokens

GPT-5.6 Terra$0.136Fits in one request

Muse Spark Open$0.075Fits in one request

Muse Spark Open costs less

Agent loop

200K input + 10K output tokens

GPT-5.6 Terra$0.520Fits in one request

Muse Spark Open$0.292Fits in one request

Muse Spark Open 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 Terra and Muse Spark Open
Specification	OpenAI GPT-5.6 Terra	Meta Muse Spark Open
Maker	OpenAI	Meta
Weights	No public weights listed	Open weights
Released	July 9, 2026	October 15, 2026
Context window	1.05M	1.05M
Input $/Mtok	$2.00	$1.25
Output $/Mtok	$12.00	$4.25
Coding index	63.9	47.4
Independent measurements behind it	6	4
Cost per solved task	$0.42	Not computable
Source	OpenRouter listing	OpenRouter listing

Questions

Is GPT-5.6 Terra better than Muse Spark Open for coding?

Pick GPT-5.6 Terra for coding: it scores 63.9 on the Vibe Coding Index against 47.4 for Muse Spark Open. Pick Muse Spark Open for output tokens 2.8x cheaper ($4.25 vs $12.00 per million) and work measured by LMArena WebDev or Vibe Code Bench (Vals AI), where it leads.

Which is cheaper, GPT-5.6 Terra or Muse Spark Open?

GPT-5.6 Terra costs $2.00 per million input tokens and $12.00 per million output tokens; Muse Spark Open costs $1.25 and $4.25. Cost per solved task is known for GPT-5.6 Terra only.

Which has the bigger context window, GPT-5.6 Terra or Muse Spark Open?

GPT-5.6 Terra, with 1.05M tokens against 1.05M.

How many benchmarks is the GPT-5.6 Terra vs Muse Spark Open comparison based on?

26 benchmarks have a result for both models as of October 22, 2026. GPT-5.6 Terra's coding index rests on 6 independent benchmarks and Muse Spark Open's on 4. Where only one model has a result, the page says so instead of naming a winner.

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<iframe src="https://llmbenchmark.ai/embed/compare/gpt-5-6-terra-vs-meta-muse-spark-open" title="GPT-5.6 Terra vs Muse Spark Open, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
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GPT-5.6 Terra or Muse Spark Open: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Knowledge

Web design

General

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

Compare next