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Model comparison

Claude Fable 5 vs Gemini 3.5 Flash

Data verified

Head-to-head evidence from 26 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

83.68/100
Margin
18.9pts
← winning
64.75/100
2 category wins1 category wins

Public leaderboard positions: Claude Fable 5 #2 (Supported); Gemini 3.5 Flash #33 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Fable 5 and Gemini 3.5 Flash share 26 comparable benchmark results. 3 of 8 categories are comparable. 8 results are unique to Claude Fable 5; 20 to Gemini 3.5 Flash.

Updated July 23, 2026
Shared results
26
Claude Fable 5 only
8
Gemini 3.5 Flash only
20
Comparable categories
3 / 8

Pick Claude Fable 5 if you want the stronger benchmark profile. Gemini 3.5 Flash 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 26 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 64.75. 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 coding, where it averages 89.2 against 53.9. The single biggest benchmark swing on the page is SWE-bench Pro, 80% to 55.1%. Gemini 3.5 Flash 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 $1.50 input / $9.00 output per 1M tokens for Gemini 3.5 Flash. That is roughly 5.6x on output cost alone. Claude Fable 5 gives you the larger context window at 1M+, compared with 1M for Gemini 3.5 Flash.

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 Gemini 3.5 Flash
CategoryClaude Fable 5ΔGemini 3.5 Flash
CodingClaude Fable 589.2Margin← 35.3Gemini 3.5 Flash53.9
MultimodalClaude Fable 557.9Margin→ 25.9Gemini 3.5 Flash83.8
AgenticClaude Fable 584.6Margin← 7.4Gemini 3.5 Flash77.2
ReasoningClaude Fable 5Not measuredMarginNo overlapGemini 3.5 Flash74.7
KnowledgeClaude Fable 5Not measuredMarginNo overlapGemini 3.5 Flash47.2
MathClaude Fable 5Not measuredMarginNo overlapGemini 3.5 Flash32.9
Inst. FollowingClaude Fable 5Not measuredMarginNo overlapGemini 3.5 Flash76.3

Decisive benchmark drivers

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

More
A · Claude Fable 5B · Gemini 3.5 Flash

  1. SWE-bench Pro

    Coding
    Source ↗
    A 80%B 55.1%
    Winner: Claude Fable 5Δ 24.9
    SWE-bench Pro: Claude Fable 5 scored 80%; Gemini 3.5 Flash scored 55.1%. Claude Fable 5 wins this benchmark.

  2. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 84.3%B 76.2%
    Winner: Claude Fable 5Δ 8.1
    Terminal-Bench 2.0: Claude Fable 5 scored 84.3%; Gemini 3.5 Flash scored 76.2%. Claude Fable 5 wins this benchmark.

  3. OSWorld-Verified

    Agentic
    Source ↗
    A 85%B 78.4%
    Winner: Claude Fable 5Δ 6.6
    OSWorld-Verified: Claude Fable 5 scored 85%; Gemini 3.5 Flash scored 78.4%. 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 5Gemini 3.5 FlashComparison
Input / output priceUSD per 1M tokensClaude Fable 5$10 input / $50 outputGemini 3.5 Flash$1.5 input / $9 outputGemini 3.5 Flash has the lower combined listed price.
Generation speedtokens per secondClaude Fable 5Not availableGemini 3.5 Flash284.2 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Fable 5Not availableGemini 3.5 Flash18.55 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Fable 51M+Gemini 3.5 Flash1MClaude Fable 5 lists the larger context window.

Benchmark Deep Dive

AgenticClaude Fable 5 wins
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
Terminal-Bench 2.0Source 84.3%76.2%Claude Fable 5 leads
OSWorld-VerifiedSource 85%78.4%Claude Fable 5 leads
GDPval-AASource 17481349Claude Fable 5 leads
AA Agentic IndexSource 52.8%37.5%Claude Fable 5 leads
τ²-bench resultsSource 98.5%95.3%Claude Fable 5 leads
GDPval-AASource 62.4%42.4%Claude Fable 5 leads
AA BriefcaseSource 1574—Not comparable
AA AutomationBenchSource 48.6%42.6%Claude Fable 5 leads
AA EnterpriseOps-GymSource 51.1%50.1%Claude Fable 5 leads
AA Harvey LABSource 93.6%—Not comparable
AA Tau3 BankingSource 26.8%—Not comparable
terminalBenchHardSource 62.9%40.9%Claude Fable 5 leads
aaTerminalBench21Source 84.6%—Not comparable
MCP AtlasSource —83.6%Not comparable
ToolathlonSource —56.5%Not comparable
Finance Agent v2Source —57.9%Not comparable
APEX-Agents-AASource —47.1%Not comparable
Gert LabsSource —61.85%Not comparable
ResearchClawBenchSource —18.0%Not comparable
CodingClaude Fable 5 wins
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
SWE-bench VerifiedSource 95%—Not comparable
SWE-bench ProSource 80%55.1%Claude Fable 5 leads
FrontierCode 1.1 MainSource 53.5%—Not comparable
Terminal-Bench 2.0Source 84.3%76.2%Claude Fable 5 leads
cursorBench31Source 70.6%49.8%Claude Fable 5 leads
cursorBench32Source 70.5%48.8%Claude Fable 5 leads
VulcanBench v3Source 87.0%—Not comparable
AA Coding IndexSource 76.5%70.1%Claude Fable 5 leads
AA-SciCodeSource 60.2%53.1%Claude Fable 5 leads
SciCodeSource —53.1%Not comparable
Vibe Code BenchSource —48.68%Not comparable
Reasoning
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
AA-LCRSource 70.0%69.3%Claude Fable 5 leads
CritPtSource 28.6%13.1%Claude Fable 5 leads
MRCRv2Source —77.3%Not comparable
MRCR 1MSource —26.6%Not comparable
ARC-AGI-2Source —72.1%Not comparable
Knowledge
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
Artificial Analysis Intelligence IndexSource 59.9%50.2%Claude Fable 5 leads
AA-GPQA DiamondSource 92.6%92.2%Claude Fable 5 leads
AA-HLESource 53.3%41.0%Claude Fable 5 leads
AA-Omniscience IndexSource 40.2%22.7%Claude Fable 5 leads
AA-Omniscience AccuracySource 61.4%51.9%Claude Fable 5 leads
AA-Omniscience Hallucination RateSource 54.9%60.7%Claude Fable 5 leads
GPQASource —92.2%Not comparable
GPQA-DSource —92.7%Not comparable
HLESource —40.2%Not comparable
Math
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
FrontierMath v2 (Tiers 1-3)Source —38.966%Not comparable
FrontierMath v2 (Tier 4)Source —14.583%Not comparable
MultimodalGemini 3.5 Flash wins
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
Blueprint-Bench 2Source 38.6%33.6%Claude Fable 5 leads
OfficeQA ProSource 57.9%—Not comparable
Design Arena WebsiteSource 13321285Claude Fable 5 leads
CharXivSource —84.2%Not comparable
MMMU-ProSource —83.6%Not comparable
AA-MMMU-ProSource —84.3%Not comparable
Inst. Following
BenchmarkClaude Fable 5Gemini 3.5 FlashResult
AA-IFBenchSource 63.5%76.3%Gemini 3.5 Flash leads
IFBenchSource —76.3%Not comparable
Frequently Asked Questions (4)

Which is better, Claude Fable 5 or Gemini 3.5 Flash?

Claude Fable 5 is ahead on BenchLM's BenchAlign leaderboard, 83.68 to 64.75. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 80% and 55.1%.

Which is better for coding, Claude Fable 5 or Gemini 3.5 Flash?

Claude Fable 5 has the edge for coding in this comparison, averaging 89.2 versus 53.9. 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 Gemini 3.5 Flash?

Claude Fable 5 has the edge for agentic tasks in this comparison, averaging 84.6 versus 77.2. Inside this category, GDPval-AA is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Fable 5 or Gemini 3.5 Flash?

Gemini 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 83.8 versus 57.9. Inside this category, Design Arena Website is the benchmark that creates the most daylight between them.

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