Head-to-head comparison

Claude Fable 5 vs. GPT-5.6 Terra

Compare published benchmark results from matching versions and cohorts, API pricing, and technical specifications. Any documented test setup differences remain visible.

shared result series: 208
distinct benchmarks: 27
latest retrieval: 2026-09-04

First modelSecond model

Specifications

General specifications

Release date, availability, context window, architecture, and published parameter counts at a glance. Undisclosed details remain marked as unavailable.

Specifications for Claude Fable 5 and GPT-5.6 Terra
Attribute	Claude Fable 5	GPT-5.6 Terra
Provider	Anthropic	OpenAI
Released	Jun 9, 2026	Jun 26, 2026
Availability	Active	Active
Model type	Proprietary	Proprietary
Parameters	Not published	Not published
Architecture	Not published	Not published
Context window	1,000,000 tokens	1,050,000 tokens
Knowledge cutoff	January 2026	February 16, 2026
Technical sources	Model, Context, Knowledge cutoff	Model, Context, Knowledge cutoff

Pricing

API pricing compared

The table compares official standard API rates per 1M tokens, including published cache pricing. Batch, fast, priority, regional surcharges, tool calls, and cloud platform pricing are excluded.

API pricing for Claude Fable 5 and GPT-5.6 Terra
Price type	Claude Fable 5	GPT-5.6 Terra
API input	$10	$2 ≤272K / $4 >272K
API output	$50	$12 ≤272K / $18 >272K
Cache read	$1	$0.2 ≤272K / $0.4 >272K
Cache write (5 min.)	$12.5	$2.5 ≤272K / $5 >272K
Cache write (1 hr.)	$20	Not listed
Price verified	07/30/2026 Source	08/11/2026 Source

Claude Fable 5GPT-5.6 Terra

API inputUSD per 1M tokens, base tier

Claude Fable 5$10

GPT-5.6 Terra$2

API outputUSD per 1M tokens, base tier

Claude Fable 5$50

GPT-5.6 Terra$12

Cache readUSD per 1M tokens, base tier

Claude Fable 5$1

GPT-5.6 Terra$0.2

Key to the marks:better valuebetter, but not conclusivetie

Pricing by provider

Direct developer pricing and provider endpoint tariffs routed through OpenRouter are listed separately. Prices are in USD per 1M tokens. Context-dependent direct tiers plus regional, Flex, Priority, and other OpenRouter tariffs remain individually identifiable.

Provider pricing for Claude Fable 5 and GPT-5.6 Terra
Model	Provider	Purchase route and tariff	Input per 1M tokens	Output per 1M tokens	Source
Claude Fable 5	Anthropic	Direct from developerStandard API	Lowest listed price: $10	Lowest listed price: $50	Source07/30/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock	Lowest listed price: $10	Lowest listed price: $50	Source09/06/2026
	Anthropic	Via OpenRouteranthropic	Lowest listed price: $10	Lowest listed price: $50	Source09/06/2026
	Azure	Via OpenRouterazure	Lowest listed price: $10	Lowest listed price: $50	Source09/06/2026
	Claude Platform on AWS	Via OpenRouterclaude-on-aws	Lowest listed price: $10	Lowest listed price: $50	Source09/06/2026
	Google	Via OpenRoutergoogle-vertex/europe	$11	$55	Source09/06/2026
	Google	Via OpenRoutergoogle-vertex/global	Lowest listed price: $10	Lowest listed price: $50	Source09/06/2026
GPT-5.6 Terra	OpenAI	Direct from developerUp to 272,000 context tokens	$2	$12	Source08/11/2026
	OpenAI	Direct from developerAbove 272,000 context tokens	$4	$18	Source08/11/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/us-east-1	$2.2	$13.2	Source09/06/2026
	Azure	Via OpenRouterazure	$2	$12	Source09/06/2026
	Azure	Via OpenRouterazure/eu	$2.2	$13.2	Source09/06/2026
	Azure	Via OpenRouterazure/us	$2.2	$13.2	Source09/06/2026
	OpenAI	Via OpenRouteropenai	$2	$12	Source09/06/2026
	OpenAI	Via OpenRouteropenai/fast	$4	$24	Source09/06/2026
	OpenAI	Via OpenRouteropenai/flex	Lowest listed price: $1	Lowest listed price: $6	Source09/06/2026

Performance

Shared benchmarks

Only published results with the same benchmark version, task, metric, and comparison cohort are paired. Different reasoning levels, agents, harnesses, or output limits appear directly in the table.

Capability profile from matched benchmarks

Each axis averages directly matched benchmark families. A value of 100 means the stronger value within this pair, not a universal quality score.

Claude Fable 5

GPT-5.6 Terra

Coding: 99.9 / 80.1 (6 benchmark families)

Reasoning: 99.9 / 95.5 (2 benchmark families)

Mathematics: 100 / 77.9 (1 benchmark family)

Knowledge: 100 / 94.7 (1 benchmark family)

Finance: 100 / 94.8 (5 benchmark families)

Legal: 100 / 62.3 (3 benchmark families)

Agentic tasks: 100 / 96.3 (1 benchmark family)

Multimodal: 100 / 96.8 (1 benchmark family)

35 matched rows from 26 benchmark families were considered. The radar shows 8 of 12 comparable categories.

Claude Fable 5GPT-5.6 Terra

Code MigrationOverall. Higher is better. No documented setup difference

Claude Fable 555.065 %

GPT-5.6 Terra47.804 %

CorpFin v2Overall. Higher is better. No documented setup difference

Claude Fable 571.834 %

GPT-5.6 Terra65.307 %

EMBOverall. Higher is better. No documented setup difference

Claude Fable 573.666 %

GPT-5.6 Terra66.205 %

Finance Agent (v2)Overall. Higher is better. No documented setup difference

Claude Fable 556.314 %

GPT-5.6 Terra54.436 %

GPQA DiamondOverall. Higher is better. No documented setup difference

Claude Fable 593.182 %

GPT-5.6 Terra90.909 %

Harvey's Legal Agent BenchmarkOverall · Task fully resolved. Higher is better. No documented setup difference

Claude Fable 511.25 %

GPT-5.6 Terra0.833 %

IOIOverall. Higher is better. No documented setup difference

Claude Fable 572.25 %

GPT-5.6 Terra65.25 %

Legal Research BenchOverall · All-pass. Higher is better. No documented setup difference

Claude Fable 549.519 %

GPT-5.6 Terra41.346 %

LegalBenchOverall. Higher is better. No documented setup difference

Claude Fable 588.561 %

GPT-5.6 Terra85.105 %

LiveBenchOverall. Higher is better. No documented setup difference

Claude Fable 582.97 points

GPT-5.6 Terra77.94 points

LiveCodeBench v6Overall. Higher is better. No documented setup difference

Claude Fable 589.778 %

GPT-5.6 Terra85.93 %

LMArena Text, Style ControlOverall. Higher is better. Test setup not documented as identical

Claude Fable 51,507.405

GPT-5.6 Terra1,466.233

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for Claude Fable 5 and GPT-5.6 Terra
Benchmark and task	Claude Fable 5	GPT-5.6 Terra	Source
Code MigrationOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner55.065 %	47.804 %	Vals AI Source details Data as of: 09/03/2026
CorpFin v2Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	Winner71.834 %	65.307 %	Vals AI Source details Data as of: 08/12/2026
EMBOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner73.666 %	66.205 %	Vals AI Source details Data as of: 09/03/2026
Finance Agent (v2)Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	Winner56.314 %	54.436 %	Vals AI Source details Data as of: 09/03/2026
GPQA DiamondOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner93.182 %	90.909 %	Vals AI Source details Data as of: 09/01/2026
Harvey's Legal Agent BenchmarkOverall · Task fully resolved Test details No documented difference in the test setupVersion: 1Metric: task resolution rateScoring: Higher is better	Winner11.25 %	0.833 %	Vals AI Source details Data as of: 09/03/2026
IOIOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner72.25 %	65.25 %	Vals AI Source details Data as of: 08/09/2026
Legal Research BenchOverall · All-pass Test details No documented difference in the test setupVersion: 1Metric: all-pass rateScoring: Higher is better	Winner49.519 %	41.346 %	Vals AI Source details Data as of: 09/03/2026
LegalBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner88.561 %	85.105 %	Vals AI Source details Data as of: 09/01/2026
LiveBenchOverall Test details No documented difference in the test setupVersion: 2026-06-25Metric: composite scoreScoring: Higher is better23 objectively scored tasks across seven categories.	Winner82.97 points	77.94 points	LiveBench Source details Data as of: 06/25/2026
LiveCodeBench v6Overall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner89.778 %	85.93 %	Vals AI Source details Data as of: 09/01/2026
LMArena Text, Style ControlOverall Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Fable 5: Snapshot: claude-fable-5, Harness: Arena text, style control GPT-5.6 Terra: Snapshot: gpt-5.6-terra-xhigh, Reasoning: xhigh, Harness: Arena text, style controlClaude Fable 5: Style-controlled Arena rating from 26,977 anonymous pairwise votes.GPT-5.6 Terra: Style-controlled Arena rating from 23,942 anonymous pairwise votes.	Higher measured value1,507.405 95% confidence interval: ±4.978The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	1,466.233 95% confidence interval: ±5.062The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	LMArena Source details Data as of: 09/01/2026
MedCodeOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner56.07 %	43.414 %	Vals AI Source details Data as of: 09/03/2026
MedScribeOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner88.522 %	82.869 %	Vals AI Source details Data as of: 09/03/2026
MMLU-ProOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner91.502 %	86.659 %	Vals AI Source details Data as of: 09/01/2026
MMMU-ProOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner89.306 %	86.474 %	Vals AI Source details Data as of: 09/01/2026
MortgageTaxOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner68.919 %	67.329 %	Vals AI Source details Data as of: 09/01/2026
ProgramBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner2 %	0.5 %	Vals AI Source details Data as of: 09/01/2026
ProofBenchOverall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better	Winner95 %	74 %	Vals AI Source details Data as of: 09/01/2026
Public Benefits Bench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better	Winner70.433 %	62.382 %	Vals AI Source details Data as of: 09/01/2026
SAGEOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner51.89 %	47.003 %	Vals AI Source details Data as of: 09/03/2026
SWE-bench VerifiedOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	95 %	Winner95.4 %	Vals AI Source details Data as of: 09/01/2026
TaxEval v2Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	Winner76.942 %	76.166 %	Vals AI Source details Data as of: 09/01/2026
Terminal-Bench 2.1Overall Test details No documented difference in the test setupVersion: 2.1Metric: accuracyScoring: Higher is better	Winner80.524 %	77.528 %	Vals AI Source details Data as of: 09/03/2026
Vals IndexOverall Test details No documented difference in the test setupVersion: 2Metric: weighted index scoreScoring: Higher is better	Winner66.036 %	59.588 %	Vals AI Source details Data as of: 09/03/2026
Vals Multimodal IndexOverall Test details No documented difference in the test setupVersion: 1.2Metric: weighted index scoreScoring: Higher is better	Winner74.154 %	65.07 %	Vals AI Source details Data as of: 08/11/2026
Vibe Code Bench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	Winner90.352 %	74.594 %	Vals AI Source details Data as of: 09/03/2026
Code MigrationCLI Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value60.087 %	26.645 %	Vals AI Source details Data as of: 08/09/2026
CorpFin v2Exact Pages Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value66.9 %	63.17 %	Vals AI Source details Data as of: 08/06/2026
EMBComps Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	70.785 %	Higher measured value72.539 %	Vals AI Source details Data as of: 08/06/2026
Finance Agent (v2)Adjustments Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value51.092 %	50.442 %	Vals AI Source details Data as of: 08/06/2026
GPQA DiamondFew-Shot CoT Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value92.929 %	89.899 %	Vals AI Source details Data as of: 08/09/2026
Harvey's Legal Agent BenchmarkAntitrust Competition · Criteria passed Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: criteria pass rateScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value92.035 %	76.449 %	Vals AI Source details Data as of: 08/07/2026
IOIIOI 2024 Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value100 %	66.167 %	Vals AI Source details Data as of: 08/09/2026
Legal Research BenchAdministrative / Regulatory · All-pass Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: all-pass rateScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	No direct winner57.576 %	No direct winner57.576 %	Vals AI Source details Data as of: 08/06/2026
LegalBenchConclusion Tasks Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value91.775 %	90.327 %	Vals AI Source details Data as of: 08/09/2026
LiveBenchAgentic coding Test details No documented difference in the test setupVersion: 2026-06-25Metric: category scoreScoring: Higher is betterAgentic coding category inside the same LiveBench release.	Winner62.2 points	54.9 points	LiveBench Source details Data as of: 06/25/2026
LiveCodeBench v6Easy Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value98.758 %	97.205 %	Vals AI Source details Data as of: 08/09/2026
LMArena Text, Style ControlBusiness, management and finance Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Fable 5: Snapshot: claude-fable-5, Harness: Arena text, style control GPT-5.6 Terra: Snapshot: gpt-5.6-terra-xhigh, Reasoning: xhigh, Harness: Arena text, style controlClaude Fable 5: Style-controlled Arena rating from 5,567 anonymous pairwise votes.GPT-5.6 Terra: Style-controlled Arena rating from 4,559 anonymous pairwise votes.	Higher measured value1,501.942 95% confidence interval: ±8.642The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	1,467.133 95% confidence interval: ±9.403The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	LMArena Source details Data as of: 09/01/2026
MMLU-ProBiology Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value93.584 %	93.026 %	Vals AI Source details Data as of: 08/09/2026
MortgageTaxNumerical Extraction Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value76.709 %	74.324 %	Vals AI Source details Data as of: 08/09/2026
ProgramBenchAlmost Resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value33 %	6.5 %	Vals AI Source details Data as of: 08/09/2026
SAGEAutomata Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 30,000 tokens	Higher measured value39.682 %	38.889 %	Vals AI Source details Data as of: 08/09/2026
SWE-bench Verified<15 min fix Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value95.876 %	77.835 %	Vals AI Source details Data as of: 08/08/2026
TaxEval v2Correctness Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	No direct winner65.822 %	No direct winner65.822 %	Vals AI Source details Data as of: 08/09/2026
Terminal-Bench 2.1Easy Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: accuracyScoring: Higher is betterGPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value100 %	83.333 %	Vals AI Source details Data as of: 08/06/2026
Vals IndexCorpFin v2 Test details Test setup not documented as identicalNo direct winnerVersion: 1.2Metric: benchmark scoreScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value71.562 %	66.434 %	Vals AI Source details Data as of: 08/09/2026
Vals Multimodal IndexCorpFin v2 Test details Test setup not documented as identicalNo direct winnerVersion: 1.2Metric: benchmark scoreScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value71.562 %	66.434 %	Vals AI Source details Data as of: 08/09/2026
Code MigrationCOBOL Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	40 %	Higher measured value65.844 %	Vals AI Source details Data as of: 08/09/2026
CorpFin v2Max Fitting Context Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value77.04 %	66.317 %	Vals AI Source details Data as of: 08/06/2026
EMBDataroom Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value85.362 %	81.591 %	Vals AI Source details Data as of: 08/06/2026
Finance Agent (v2)All-Pass Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value45.694 %	40.448 %	Vals AI Source details Data as of: 08/06/2026
GPQA DiamondZero-Shot CoT Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value93.434 %	91.919 %	Vals AI Source details Data as of: 08/09/2026
Harvey's Legal Agent BenchmarkAntitrust Competition · Task fully resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: task resolution rateScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	No direct winner0 %	No direct winner0 %	Vals AI Source details Data as of: 08/07/2026
IOIIOI 2025 Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	44.5 %	Higher measured value64.333 %	Vals AI Source details Data as of: 08/09/2026
Legal Research BenchAdministrative / Regulatory · Weighted partial credit Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: weighted partial-credit scoreScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value90.224 %	86.696 %	Vals AI Source details Data as of: 08/06/2026
LegalBenchInterpretation Tasks Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value86.863 %	83.178 %	Vals AI Source details Data as of: 08/09/2026
LiveBenchCoding Test details No documented difference in the test setupVersion: 2026-06-25Metric: category scoreScoring: Higher is betterCoding category inside the same LiveBench release.	Winner86 points	78.2 points	LiveBench Source details Data as of: 06/25/2026
LiveCodeBench v6Hard Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value79.714 %	72.857 %	Vals AI Source details Data as of: 08/09/2026
LMArena Text, Style ControlChinese Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Fable 5: Snapshot: claude-fable-5, Harness: Arena text, style control GPT-5.6 Terra: Snapshot: gpt-5.6-terra-xhigh, Reasoning: xhigh, Harness: Arena text, style controlClaude Fable 5: Style-controlled Arena rating from 1,671 anonymous pairwise votes.GPT-5.6 Terra: Style-controlled Arena rating from 1,627 anonymous pairwise votes.	Higher measured value1,554.267 95% confidence interval: ±15.295The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	1,518.544 95% confidence interval: ±15.369The Arena score measures human preference rather than a fixed capability test. The confidence interval and model configuration are part of the result.	LMArena Source details Data as of: 09/01/2026
MMLU-ProBusiness Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value93.156 %	90.875 %	Vals AI Source details Data as of: 08/09/2026
MortgageTaxSemantic Extraction Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value61.129 %	60.334 %	Vals AI Source details Data as of: 08/09/2026
ProgramBenchFully Resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 128,000 tokens	Higher measured value2 %	0.5 %	Vals AI Source details Data as of: 08/09/2026
SAGELinear Algebra Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Fable 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens GPT-5.6 Terra: Reasoning: xhigh, Output limit: 30,000 tokens	Higher measured value71.544 %	64.025 %	Vals AI Source details Data as of: 08/09/2026
Key to the marks:better valuebetter, but not conclusivetie

How to read this comparison

Winning one benchmark is not an overall verdict

Your workload, budget, and required context length matter most. A coding benchmark says little about visual understanding or agent performance.

The standard price table uses direct developer rates. The provider comparison labels OpenRouter endpoints, regions, and special tariffs separately.

Every result links to its measurement source and retrieval date. Labels distinguish vendor reports, official benchmark leaderboards, and independent evaluations. Disputed or archived results are excluded.

More matchups

Compare Claude Fable 5 and GPT-5.6 Terra with other leading models using the same data and benchmark logic.

View the complete LLM comparison