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Model comparison

Claude Opus 4.8 vs GPT-5.6 Terra

Data verified

Head-to-head evidence from 31 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

78.34/100
Margin
5.8pts
← winning
72.57/100
1 category wins4 category wins

Public leaderboard positions: Claude Opus 4.8 #5 (Supported); GPT-5.6 Terra #11 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Opus 4.8 and GPT-5.6 Terra share 31 comparable benchmark results. 5 of 8 categories are comparable. 22 results are unique to Claude Opus 4.8; 13 to GPT-5.6 Terra.

Updated July 23, 2026
Shared results
31
Claude Opus 4.8 only
22
GPT-5.6 Terra only
13
Comparable categories
5 / 8

Pick Claude Opus 4.8 if you want the stronger benchmark profile. GPT-5.6 Terra only becomes the better choice if knowledge is the priority or you want the cheaper token bill.

Confidence note. This is a partial-evidence comparison with 31 shared benchmark results across 6 evidence categories; 5 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Claude Opus 4.8 is clearly ahead on the BenchAlign aggregate, 78.34 to 72.57. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Opus 4.8's sharpest advantage is in coding, where it averages 81.1 against 63.4. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 47.241% to 84.900%. GPT-5.6 Terra does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.

Claude Opus 4.8 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $2.50 input / $15.00 output per 1M tokens for GPT-5.6 Terra.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for Claude Opus 4.8 and GPT-5.6 Terra
CategoryClaude Opus 4.8ΔGPT-5.6 Terra
KnowledgeClaude Opus 4.862.7Margin→ 30.2GPT-5.6 Terra92.9
MathClaude Opus 4.853.9Margin→ 26.9GPT-5.6 Terra80.8
CodingClaude Opus 4.881.1Margin← 17.7GPT-5.6 Terra63.4
AgenticClaude Opus 4.880.3Margin→ 7.1GPT-5.6 Terra87.4
MultimodalClaude Opus 4.877.0Margin→ 3.7GPT-5.6 Terra80.7

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · Claude Opus 4.8B · GPT-5.6 Terra

  1. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 47.241%B 84.900%
    Winner: GPT-5.6 TerraΔ 37.7
    FrontierMath v2 (Tiers 1-3): Claude Opus 4.8 scored 47.241%; GPT-5.6 Terra scored 84.900%. GPT-5.6 Terra wins this benchmark.

  2. FrontierMath v2 (Tier 4)

    Math
    Source ↗
    A 31.250%B 68.300%
    Winner: GPT-5.6 TerraΔ 37.1
    FrontierMath v2 (Tier 4): Claude Opus 4.8 scored 31.250%; GPT-5.6 Terra scored 68.300%. GPT-5.6 Terra wins this benchmark.

  3. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 74.6%B 87.4%
    Winner: GPT-5.6 TerraΔ 12.8
    Terminal-Bench 2.0: Claude Opus 4.8 scored 74.6%; GPT-5.6 Terra scored 87.4%. GPT-5.6 Terra wins this benchmark.

  4. SWE-bench Pro

    Coding
    Source ↗
    A 69.2%B 63.4%
    Winner: Claude Opus 4.8Δ 5.8
    SWE-bench Pro: Claude Opus 4.8 scored 69.2%; GPT-5.6 Terra scored 63.4%. Claude Opus 4.8 wins this benchmark.

  5. BrowseComp

    Agentic
    Source ↗
    A 84.3%B 87.5%
    Winner: GPT-5.6 TerraΔ 3.2
    BrowseComp: Claude Opus 4.8 scored 84.3%; GPT-5.6 Terra scored 87.5%. GPT-5.6 Terra wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricClaude Opus 4.8GPT-5.6 TerraComparison
Input / output priceUSD per 1M tokensClaude Opus 4.8$5 input / $25 outputGPT-5.6 Terra$2.5 input / $15 outputGPT-5.6 Terra has the lower combined listed price.
Generation speedtokens per secondClaude Opus 4.8Not availableGPT-5.6 TerraNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Opus 4.8Not availableGPT-5.6 TerraNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Opus 4.81MGPT-5.6 Terra1MListed context windows are equal.

Benchmark Deep Dive

AgenticGPT-5.6 Terra wins
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
Terminal-Bench 2.0Source 74.6%87.4%GPT-5.6 Terra leads
BrowseCompSource 84.3%87.5%GPT-5.6 Terra leads
DeepSearchQASource 93.1%—Not comparable
OSWorld-VerifiedSource 83.4%—Not comparable
Finance Agent v2Source 53.9%—Not comparable
GDPval-AASource 15941581Claude Opus 4.8 leads
MCP AtlasSource 82.2%—Not comparable
ToolathlonSource 59.9%53.1%Claude Opus 4.8 leads
Gert LabsSource 72.97%—Not comparable
AA Agentic IndexSource 47.2%47.4%GPT-5.6 Terra leads
τ²-bench resultsSource 94.4%86.3%Claude Opus 4.8 leads
GDPval-AASource 54.7%54.1%Claude Opus 4.8 leads
ResearchClawBenchSource 21.1%—Not comparable
OSWorld 2.0Source 20.6%50.2%GPT-5.6 Terra leads
AA BriefcaseSource 1347—Not comparable
AA AutomationBenchSource 48.5%45.6%Claude Opus 4.8 leads
AA EnterpriseOps-GymSource 44.0%—Not comparable
AA Harvey LABSource 91.1%85.2%Claude Opus 4.8 leads
AA Tau3 BankingSource 27.6%31.8%GPT-5.6 Terra leads
terminalBenchHardSource 58.3%57.6%Claude Opus 4.8 leads
aaTerminalBench21Source 84.6%88%GPT-5.6 Terra leads
CyberGymSource —81.8%Not comparable
ExploitGymSource —23.2%Not comparable
AA ITBenchSource —51.0%Not comparable
APEX-Agents-AASource —38.9%Not comparable
CodingClaude Opus 4.8 wins
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
SWE-bench VerifiedSource 88.6%—Not comparable
SWE-bench ProSource 69.2%63.4%Claude Opus 4.8 leads
SWE MultilingualSource 84.4%—Not comparable
SWE MultimodalSource 38.4%—Not comparable
Terminal-Bench 2.0Source 74.6%87.4%GPT-5.6 Terra leads
cursorBench31Source 58.4%—Not comparable
cursorBench32Source 62.3%64.9%GPT-5.6 Terra leads
AA Coding IndexSource 74.3%76.7%GPT-5.6 Terra leads
AA-SciCodeSource 53.5%53.9%GPT-5.6 Terra leads
FrontierCode 1.1 MainSource 46.5%—Not comparable
deepSweSource —69.6%Not comparable
FrontierCode 1.1 ExtendedSource —55.8%Not comparable
Reasoning
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
AA-LCRSource 67.7%74.0%GPT-5.6 Terra leads
CritPtSource 20.9%30.0%GPT-5.6 Terra leads
ARC-AGI-3Source —0.8%Not comparable
KnowledgeGPT-5.6 Terra wins
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
GPQASource 93.6%92.9%Claude Opus 4.8 leads
GPQA-DSource 93.6%92.9%Claude Opus 4.8 leads
HLESource 57.9%—Not comparable
HLE w/o toolsSource 49.8%—Not comparable
Artificial Analysis Intelligence IndexSource 55.7%55.0%Claude Opus 4.8 leads
AA-GPQA DiamondSource 92.0%92.5%GPT-5.6 Terra leads
AA-HLESource 45.7%41.8%Claude Opus 4.8 leads
AA-Omniscience IndexSource 27.4%-0.2%Claude Opus 4.8 leads
AA-Omniscience AccuracySource 46.6%45.9%Claude Opus 4.8 leads
AA-Omniscience Hallucination RateSource 35.9%85.2%Claude Opus 4.8 leads
HealthBench ProfessionalSource —57.7%Not comparable
HealthBench HardSource —32.7%Not comparable
MathGPT-5.6 Terra wins
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
USAMO 2026Source 96.7%—Not comparable
FrontierMath v2 (Tiers 1-3)Source 47.241%84.900%GPT-5.6 Terra leads
FrontierMath v2 (Tier 4)Source 31.250%68.300%GPT-5.6 Terra leads
FrontierMath (legacy)Source —84.9%Not comparable
Multilingual
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
INCLUDESource 87.6%—Not comparable
MultimodalGPT-5.6 Terra wins
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
OfficeQA ProSource 66.2%—Not comparable
ScreenSpot ProSource 87.9%—Not comparable
CharXivSource 89.9%—Not comparable
CharXiv w/o toolsSource 80.5%—Not comparable
Design Arena WebsiteSource 1270—Not comparable
MMMU-ProSource —80.7%Not comparable
MMMU-Pro w/ PythonSource —82%Not comparable
AA-MMMU-ProSource —80.7%Not comparable
Inst. Following
BenchmarkClaude Opus 4.8GPT-5.6 TerraResult
AA-IFBenchSource 62.2%71.2%GPT-5.6 Terra leads
Frequently Asked Questions (6)

Which is better, Claude Opus 4.8 or GPT-5.6 Terra?

Claude Opus 4.8 is ahead on BenchLM's BenchAlign leaderboard, 78.34 to 72.57. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 47.241% and 84.900%.

Which is better for knowledge tasks, Claude Opus 4.8 or GPT-5.6 Terra?

GPT-5.6 Terra has the edge for knowledge tasks in this comparison, averaging 92.9 versus 62.7. Inside this category, AA-Omniscience Hallucination Rate is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Opus 4.8 or GPT-5.6 Terra?

Claude Opus 4.8 has the edge for coding in this comparison, averaging 81.1 versus 63.4. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for math, Claude Opus 4.8 or GPT-5.6 Terra?

GPT-5.6 Terra has the edge for math in this comparison, averaging 80.8 versus 53.9. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Opus 4.8 or GPT-5.6 Terra?

GPT-5.6 Terra has the edge for agentic tasks in this comparison, averaging 87.4 versus 80.3. Inside this category, OSWorld 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Opus 4.8 or GPT-5.6 Terra?

GPT-5.6 Terra has the edge for multimodal and grounded tasks in this comparison, averaging 80.7 versus 77. Claude Opus 4.8 stays close enough that the answer can still flip depending on your workload.

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