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Model comparison

Claude Opus 4.5 vs Gemini 3.5 Flash

Data verified

Head-to-head evidence from 26 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

64.22/100
Margin
0.5pts
winning →
64.75/100
3 category wins4 category wins

Public leaderboard positions: Claude Opus 4.5 #34 (Supported); Gemini 3.5 Flash #33 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Opus 4.5 and Gemini 3.5 Flash share 26 comparable benchmark results. 7 of 8 categories are comparable. 33 results are unique to Claude Opus 4.5; 20 to Gemini 3.5 Flash.

Updated July 23, 2026
Shared results
26
Claude Opus 4.5 only
33
Gemini 3.5 Flash only
20
Comparable categories
7 / 8

Pick Gemini 3.5 Flash if you want the stronger benchmark profile. Claude Opus 4.5 only becomes the better choice if mathematics is the priority or you would rather avoid the extra latency and token burn of a reasoning model.

Confidence note. This is a partial-evidence comparison with 26 shared benchmark results across 7 evidence categories; 7 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Gemini 3.5 Flash has the cleaner BenchAlign overall profile here, landing at 64.75 versus 64.22. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

Gemini 3.5 Flash's sharpest advantage is in agentic, where it averages 77.2 against 62.6. The single biggest benchmark swing on the page is IFBench, 58% to 76.3%. Claude Opus 4.5 does hit back in mathematics, so the answer changes if that is the part of the workload you care about most.

Claude Opus 4.5 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $1.50 input / $9.00 output per 1M tokens for Gemini 3.5 Flash. That is roughly 2.8x on output cost alone. Gemini 3.5 Flash 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. Gemini 3.5 Flash 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 Opus 4.5 and Gemini 3.5 Flash
CategoryClaude Opus 4.5ΔGemini 3.5 Flash
MathClaude Opus 4.557.5Margin← 24.6Gemini 3.5 Flash32.9
CodingClaude Opus 4.571.7Margin← 17.8Gemini 3.5 Flash53.9
AgenticClaude Opus 4.562.6Margin→ 14.6Gemini 3.5 Flash77.2
MultimodalClaude Opus 4.569.9Margin→ 13.9Gemini 3.5 Flash83.8
KnowledgeClaude Opus 4.558.1Margin← 10.9Gemini 3.5 Flash47.2
ReasoningClaude Opus 4.564.4Margin→ 10.3Gemini 3.5 Flash74.7
Inst. FollowingClaude Opus 4.569.5Margin→ 6.8Gemini 3.5 Flash76.3
MultilingualClaude Opus 4.585.7MarginNo overlapGemini 3.5 FlashNot measured

Decisive benchmark drivers

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

More
A · Claude Opus 4.5B · Gemini 3.5 Flash

  1. IFBench

    Inst. Following
    Source ↗
    A 58%B 76.3%
    Winner: Gemini 3.5 FlashΔ 18.3
    IFBench: Claude Opus 4.5 scored 58%; Gemini 3.5 Flash scored 76.3%. Gemini 3.5 Flash wins this benchmark.

  2. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 20.690%B 38.966%
    Winner: Gemini 3.5 FlashΔ 18.3
    FrontierMath v2 (Tiers 1-3): Claude Opus 4.5 scored 20.690%; Gemini 3.5 Flash scored 38.966%. Gemini 3.5 Flash wins this benchmark.

  3. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 59.3%B 76.2%
    Winner: Gemini 3.5 FlashΔ 16.9
    Terminal-Bench 2.0: Claude Opus 4.5 scored 59.3%; Gemini 3.5 Flash scored 76.2%. Gemini 3.5 Flash wins this benchmark.

  4. CharXiv

    Multimodal
    Source ↗
    A 68.5%B 84.2%
    Winner: Gemini 3.5 FlashΔ 15.7
    CharXiv: Claude Opus 4.5 scored 68.5%; Gemini 3.5 Flash scored 84.2%. Gemini 3.5 Flash wins this benchmark.

  5. MMMU-Pro

    Multimodal
    Source ↗
    A 70.6%B 83.6%
    Winner: Gemini 3.5 FlashΔ 13
    MMMU-Pro: Claude Opus 4.5 scored 70.6%; Gemini 3.5 Flash scored 83.6%. Gemini 3.5 Flash wins this benchmark.

Operational comparison

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

MetricClaude Opus 4.5Gemini 3.5 FlashComparison
Input / output priceUSD per 1M tokensClaude Opus 4.5$5 input / $25 outputGemini 3.5 Flash$1.5 input / $9 outputGemini 3.5 Flash has the lower combined listed price.
Generation speedtokens per secondClaude Opus 4.546 tok/sGemini 3.5 Flash284.2 tok/sGemini 3.5 Flash has the higher measured throughput.
First-answer latencyseconds to first tokenClaude Opus 4.51.01 sGemini 3.5 Flash18.55 sClaude Opus 4.5 reaches the first token sooner.
Context windowmaximum listed tokensClaude Opus 4.5200KGemini 3.5 Flash1MGemini 3.5 Flash lists the larger context window.

Benchmark Deep Dive

AgenticGemini 3.5 Flash wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
Terminal-Bench 2.0Source 59.3%76.2%Gemini 3.5 Flash leads
OSWorld-VerifiedSource 66.3%78.4%Gemini 3.5 Flash leads
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%56.5%Gemini 3.5 Flash leads
MCP AtlasSource 42.3%83.6%Gemini 3.5 Flash leads
MCP-TasksSource 71.8%—Not comparable
WideResearchSource 76.4%—Not comparable
CyberGymSource 50.6%—Not comparable
τ²-bench resultsSource 86.3%95.3%Gemini 3.5 Flash leads
Gert LabsSource 64.23%61.85%Claude Opus 4.5 leads
JobBenchSource 32.3%—Not comparable
Finance Agent v2Source —57.9%Not comparable
GDPval-AASource —1349Not comparable
GDPval-AASource —42.4%Not comparable
AA Agentic IndexSource —37.5%Not comparable
APEX-Agents-AASource —47.1%Not comparable
ResearchClawBenchSource —18.0%Not comparable
AA AutomationBenchSource —42.6%Not comparable
AA EnterpriseOps-GymSource —50.1%Not comparable
terminalBenchHardSource —40.9%Not comparable
CodingClaude Opus 4.5 wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
SWE-bench VerifiedSource 80.9%—Not comparable
LiveCodeBench v6Source 84.8%—Not comparable
SWE-bench ProSource 57.1%55.1%Claude Opus 4.5 leads
SWE MultilingualSource 77.5%—Not comparable
NL2RepoSource 43.2%—Not comparable
AA-SciCodeSource 47.0%53.1%Gemini 3.5 Flash leads
Terminal-Bench 2.0Source —76.2%Not comparable
SciCodeSource —53.1%Not comparable
Vibe Code BenchSource —48.68%Not comparable
cursorBench31Source —49.8%Not comparable
cursorBench32Source —48.8%Not comparable
AA Coding IndexSource —70.1%Not comparable
ReasoningGemini 3.5 Flash wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
LongBench v2Source 64.4%—Not comparable
AI-NeedleSource 74%—Not comparable
AA-LCRSource 65.3%69.3%Gemini 3.5 Flash leads
CritPtSource 0.3%13.1%Gemini 3.5 Flash leads
MRCRv2Source —77.3%Not comparable
MRCR 1MSource —26.6%Not comparable
ARC-AGI-2Source —72.1%Not comparable
KnowledgeClaude Opus 4.5 wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
GPQASource 87%92.2%Gemini 3.5 Flash leads
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%40.2%Gemini 3.5 Flash leads
Artificial Analysis Intelligence IndexSource 34.7%50.2%Gemini 3.5 Flash leads
AA-GPQA DiamondSource 81.0%92.2%Gemini 3.5 Flash leads
AA-HLESource 12.9%41.0%Gemini 3.5 Flash leads
AA-Omniscience IndexSource -3.9%22.7%Gemini 3.5 Flash leads
AA-Omniscience AccuracySource 40.7%51.9%Gemini 3.5 Flash leads
AA-Omniscience Hallucination RateSource 75.4%60.7%Gemini 3.5 Flash leads
AA MMLU-ProSource 88.9%—Not comparable
GPQA-DSource —92.7%Not comparable
MathClaude Opus 4.5 wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
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%38.966%Gemini 3.5 Flash leads
FrontierMath v2 (Tier 4)Source 4.167%14.583%Gemini 3.5 Flash leads
Multilingual
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
MMLU-ProXSource 85.7%—Not comparable
NOVA-63Source 56.7%—Not comparable
MultimodalGemini 3.5 Flash wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
MMMU-ProSource 70.6%83.6%Gemini 3.5 Flash leads
MathVisionSource 74.3%—Not comparable
CharXivSource 68.5%84.2%Gemini 3.5 Flash leads
VideoMMMUSource 84.4%—Not comparable
ScreenSpot ProSource 45.7%—Not comparable
V*Source 67.0%—Not comparable
AA-MMMU-ProSource 71.2%84.3%Gemini 3.5 Flash leads
Design Arena WebsiteSource 12771285Gemini 3.5 Flash leads
Blueprint-Bench 2Source —33.6%Not comparable
Inst. FollowingGemini 3.5 Flash wins
BenchmarkClaude Opus 4.5Gemini 3.5 FlashResult
IFEvalSource 90.9%—Not comparable
IFBenchSource 58%76.3%Gemini 3.5 Flash leads
AA-IFBenchSource 43.0%76.3%Gemini 3.5 Flash leads
Frequently Asked Questions (8)

Which is better, Claude Opus 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash is ahead on BenchLM's BenchAlign leaderboard, 64.75 to 64.22. The biggest single separator in this matchup is IFBench, where the scores are 58% and 76.3%.

Which is better for knowledge tasks, Claude Opus 4.5 or Gemini 3.5 Flash?

Claude Opus 4.5 has the edge for knowledge tasks in this comparison, averaging 58.1 versus 47.2. Inside this category, AA-HLE is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Opus 4.5 or Gemini 3.5 Flash?

Claude Opus 4.5 has the edge for coding in this comparison, averaging 71.7 versus 53.9. Inside this category, AA-SciCode is the benchmark that creates the most daylight between them.

Which is better for math, Claude Opus 4.5 or Gemini 3.5 Flash?

Claude Opus 4.5 has the edge for math in this comparison, averaging 57.5 versus 32.9. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.

Which is better for reasoning, Claude Opus 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash has the edge for reasoning in this comparison, averaging 74.7 versus 64.4. Inside this category, CritPt is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Opus 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash has the edge for agentic tasks in this comparison, averaging 77.2 versus 62.6. Inside this category, MCP Atlas is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Opus 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 83.8 versus 69.9. Inside this category, CharXiv is the benchmark that creates the most daylight between them.

Which is better for instruction following, Claude Opus 4.5 or Gemini 3.5 Flash?

Gemini 3.5 Flash has the edge for instruction following in this comparison, averaging 76.3 versus 69.5. Inside this category, AA-IFBench is the benchmark that creates the most daylight between them.

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