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Model comparison

Claude Fable 5 vs Claude Opus 4.5

Data verified

Head-to-head evidence from 16 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

83.68/100
Margin
19.5pts
← winning
64.22/100
2 category wins1 category wins

Public leaderboard positions: Claude Fable 5 #2 (Supported); Claude Opus 4.5 #34 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Fable 5 and Claude Opus 4.5 share 16 comparable benchmark results. 3 of 8 categories are comparable. 18 results are unique to Claude Fable 5; 43 to Claude Opus 4.5.

Updated July 23, 2026
Shared results
16
Claude Fable 5 only
18
Claude Opus 4.5 only
43
Comparable categories
3 / 8

Pick Claude Fable 5 if you want the stronger benchmark profile. Claude Opus 4.5 only becomes the better choice if multimodal & grounded is the priority or you want the cheaper token bill.

Confidence note. This is a partial-evidence comparison with 16 shared benchmark results across 6 evidence categories; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Claude Fable 5 is clearly ahead on the BenchAlign aggregate, 83.68 to 64.22. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Fable 5's sharpest advantage is in agentic, where it averages 84.6 against 62.6. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 84.3% to 59.3%. Claude Opus 4.5 does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.

Claude Fable 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $5.00 input / $25.00 output per 1M tokens for Claude Opus 4.5. That is roughly 2.0x on output cost alone. Claude Fable 5 is the reasoning model in the pair, while Claude Opus 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Claude Fable 5 gives you the larger context window at 1M+, compared with 200K for Claude Opus 4.5.

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 Fable 5 and Claude Opus 4.5
CategoryClaude Fable 5ΔClaude Opus 4.5
AgenticClaude Fable 584.6Margin← 22.0Claude Opus 4.562.6
CodingClaude Fable 589.2Margin← 17.5Claude Opus 4.571.7
MultimodalClaude Fable 557.9Margin→ 12.0Claude Opus 4.569.9
ReasoningClaude Fable 5Not measuredMarginNo overlapClaude Opus 4.564.4
KnowledgeClaude Fable 5Not measuredMarginNo overlapClaude Opus 4.558.1
MathClaude Fable 5Not measuredMarginNo overlapClaude Opus 4.557.5
MultilingualClaude Fable 5Not measuredMarginNo overlapClaude Opus 4.585.7
Inst. FollowingClaude Fable 5Not measuredMarginNo overlapClaude Opus 4.569.5

Decisive benchmark drivers

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

More
A · Claude Fable 5B · Claude Opus 4.5

  1. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 84.3%B 59.3%
    Winner: Claude Fable 5Δ 25
    Terminal-Bench 2.0: Claude Fable 5 scored 84.3%; Claude Opus 4.5 scored 59.3%. Claude Fable 5 wins this benchmark.

  2. SWE-bench Pro

    Coding
    Source ↗
    A 80%B 57.1%
    Winner: Claude Fable 5Δ 22.9
    SWE-bench Pro: Claude Fable 5 scored 80%; Claude Opus 4.5 scored 57.1%. Claude Fable 5 wins this benchmark.

  3. OSWorld-Verified

    Agentic
    Source ↗
    A 85%B 66.3%
    Winner: Claude Fable 5Δ 18.7
    OSWorld-Verified: Claude Fable 5 scored 85%; Claude Opus 4.5 scored 66.3%. Claude Fable 5 wins this benchmark.

  4. SWE-bench Verified

    Coding
    Source ↗
    A 95%B 80.9%
    Winner: Claude Fable 5Δ 14.1
    SWE-bench Verified: Claude Fable 5 scored 95%; Claude Opus 4.5 scored 80.9%. Claude Fable 5 wins this benchmark.

Operational comparison

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

MetricClaude Fable 5Claude Opus 4.5Comparison
Input / output priceUSD per 1M tokensClaude Fable 5$10 input / $50 outputClaude Opus 4.5$5 input / $25 outputClaude Opus 4.5 has the lower combined listed price.
Generation speedtokens per secondClaude Fable 5Not availableClaude Opus 4.546 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Fable 5Not availableClaude Opus 4.51.01 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Fable 51M+Claude Opus 4.5200KClaude Fable 5 lists the larger context window.

Benchmark Deep Dive

AgenticClaude Fable 5 wins
BenchmarkClaude Fable 5Claude Opus 4.5Result
Terminal-Bench 2.0Source 84.3%59.3%Claude Fable 5 leads
OSWorld-VerifiedSource 85%66.3%Claude Fable 5 leads
GDPval-AASource 1748—Not comparable
AA Agentic IndexSource 52.8%—Not comparable
τ²-bench resultsSource 98.5%86.3%Claude Fable 5 leads
GDPval-AASource 62.4%—Not comparable
AA BriefcaseSource 1574—Not comparable
AA AutomationBenchSource 48.6%—Not comparable
AA EnterpriseOps-GymSource 51.1%—Not comparable
AA Harvey LABSource 93.6%—Not comparable
AA Tau3 BankingSource 26.8%—Not comparable
terminalBenchHardSource 62.9%—Not comparable
aaTerminalBench21Source 84.6%—Not comparable
OSWorldSource —66.3%Not comparable
Claw-EvalSource —59.6%Not comparable
QwenClawBenchSource —52.3%Not comparable
τ³-bench resultsSource —70.2%Not comparable
VITA-BenchSource —23.3%Not comparable
DeepPlanningSource —26.4%Not comparable
ToolathlonSource —43.5%Not comparable
MCP AtlasSource —42.3%Not comparable
MCP-TasksSource —71.8%Not comparable
WideResearchSource —76.4%Not comparable
CyberGymSource —50.6%Not comparable
Gert LabsSource —64.23%Not comparable
JobBenchSource —32.3%Not comparable
CodingClaude Fable 5 wins
BenchmarkClaude Fable 5Claude Opus 4.5Result
SWE-bench VerifiedSource 95%80.9%Claude Fable 5 leads
SWE-bench ProSource 80%57.1%Claude Fable 5 leads
FrontierCode 1.1 MainSource 53.5%—Not comparable
Terminal-Bench 2.0Source 84.3%—Not comparable
cursorBench31Source 70.6%—Not comparable
cursorBench32Source 70.5%—Not comparable
VulcanBench v3Source 87.0%—Not comparable
AA Coding IndexSource 76.5%—Not comparable
AA-SciCodeSource 60.2%47.0%Claude Fable 5 leads
LiveCodeBench v6Source —84.8%Not comparable
SWE MultilingualSource —77.5%Not comparable
NL2RepoSource —43.2%Not comparable
Reasoning
BenchmarkClaude Fable 5Claude Opus 4.5Result
AA-LCRSource 70.0%65.3%Claude Fable 5 leads
CritPtSource 28.6%0.3%Claude Fable 5 leads
LongBench v2Source —64.4%Not comparable
AI-NeedleSource —74%Not comparable
Knowledge
BenchmarkClaude Fable 5Claude Opus 4.5Result
Artificial Analysis Intelligence IndexSource 59.9%34.7%Claude Fable 5 leads
AA-GPQA DiamondSource 92.6%81.0%Claude Fable 5 leads
AA-HLESource 53.3%12.9%Claude Fable 5 leads
AA-Omniscience IndexSource 40.2%-3.9%Claude Fable 5 leads
AA-Omniscience AccuracySource 61.4%40.7%Claude Fable 5 leads
AA-Omniscience Hallucination RateSource 54.9%75.4%Claude Fable 5 leads
GPQASource —87%Not comparable
SuperGPQASource —70.6%Not comparable
MMLU-ProSource —89.5%Not comparable
MMLU-ReduxSource —96.6%Not comparable
C-EvalSource —92.2%Not comparable
HLESource —30.8%Not comparable
AA MMLU-ProSource —88.9%Not comparable
Math
BenchmarkClaude Fable 5Claude Opus 4.5Result
AIME26Source —95.1%Not comparable
HMMT Feb 2025Source —92.9%Not comparable
HMMT Nov 2025Source —93.3%Not comparable
HMMT Feb 2026Source —85.3%Not comparable
MMAnswerBenchSource —84.0%Not comparable
FrontierMath v2 (Tiers 1-3)Source —20.690%Not comparable
FrontierMath v2 (Tier 4)Source —4.167%Not comparable
Multilingual
BenchmarkClaude Fable 5Claude Opus 4.5Result
MMLU-ProXSource —85.7%Not comparable
NOVA-63Source —56.7%Not comparable
MultimodalClaude Opus 4.5 wins
BenchmarkClaude Fable 5Claude Opus 4.5Result
Blueprint-Bench 2Source 38.6%—Not comparable
OfficeQA ProSource 57.9%—Not comparable
Design Arena WebsiteSource 13321277Claude Fable 5 leads
MMMU-ProSource —70.6%Not comparable
MathVisionSource —74.3%Not comparable
CharXivSource —68.5%Not comparable
VideoMMMUSource —84.4%Not comparable
ScreenSpot ProSource —45.7%Not comparable
V*Source —67.0%Not comparable
AA-MMMU-ProSource —71.2%Not comparable
Inst. Following
BenchmarkClaude Fable 5Claude Opus 4.5Result
AA-IFBenchSource 63.5%43.0%Claude Fable 5 leads
IFEvalSource —90.9%Not comparable
IFBenchSource —58%Not comparable
Frequently Asked Questions (4)

Which is better, Claude Fable 5 or Claude Opus 4.5?

Claude Fable 5 is ahead on BenchLM's BenchAlign leaderboard, 83.68 to 64.22. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 84.3% and 59.3%.

Which is better for coding, Claude Fable 5 or Claude Opus 4.5?

Claude Fable 5 has the edge for coding in this comparison, averaging 89.2 versus 71.7. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Fable 5 or Claude Opus 4.5?

Claude Fable 5 has the edge for agentic tasks in this comparison, averaging 84.6 versus 62.6. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Fable 5 or Claude Opus 4.5?

Claude Opus 4.5 has the edge for multimodal and grounded tasks in this comparison, averaging 69.9 versus 57.9. Inside this category, Design Arena Website is the benchmark that creates the most daylight between them.

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