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Model comparison

Claude Opus 4.5 vs Gemini 2.5 Flash

Data verified

Head-to-head evidence from 15 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

64.22/100
Margin
16.1pts
← winning
48.09/100
1 category wins0 category wins

Public leaderboard positions: Claude Opus 4.5 #34 (Supported); Gemini 2.5 Flash #130 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Opus 4.5 and Gemini 2.5 Flash share 15 comparable benchmark results. 1 of 8 categories are comparable. 44 results are unique to Claude Opus 4.5; 0 to Gemini 2.5 Flash.

Updated July 22, 2026
Shared results
15
Claude Opus 4.5 only
44
Gemini 2.5 Flash only
0
Comparable categories
1 / 8

Pick Claude Opus 4.5 if you want the stronger benchmark profile. Gemini 2.5 Flash only becomes the better choice if you want the cheaper token bill or you need the larger 1M context window.

Confidence note. This is a partial-evidence comparison with 15 shared benchmark results across 7 evidence categories; 1 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 4.5 is clearly ahead on the BenchAlign aggregate, 64.22 to 48.09. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Opus 4.5's sharpest advantage is in mathematics, where it averages 57.5 against 4.7. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 20.690% to 4.844%.

Claude Opus 4.5 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $0.30 input / $2.50 output per 1M tokens for Gemini 2.5 Flash. That is roughly 10.0x on output cost alone. Gemini 2.5 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 2.5 Flash
CategoryClaude Opus 4.5ΔGemini 2.5 Flash
MathClaude Opus 4.557.5Margin← 52.8Gemini 2.5 Flash4.7
AgenticClaude Opus 4.562.6MarginNo overlapGemini 2.5 FlashNot measured
CodingClaude Opus 4.571.7MarginNo overlapGemini 2.5 FlashNot measured
ReasoningClaude Opus 4.564.4MarginNo overlapGemini 2.5 FlashNot measured
KnowledgeClaude Opus 4.558.1MarginNo overlapGemini 2.5 FlashNot measured
MultilingualClaude Opus 4.585.7MarginNo overlapGemini 2.5 FlashNot measured
MultimodalClaude Opus 4.569.9MarginNo overlapGemini 2.5 FlashNot measured
Inst. FollowingClaude Opus 4.569.5MarginNo overlapGemini 2.5 FlashNot measured

Decisive benchmark drivers

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

More
A · Claude Opus 4.5B · Gemini 2.5 Flash

  1. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 20.690%B 4.844%
    Winner: Claude Opus 4.5Δ 15.8
    FrontierMath v2 (Tiers 1-3): Claude Opus 4.5 scored 20.690%; Gemini 2.5 Flash scored 4.844%. Claude Opus 4.5 wins this benchmark.

Operational comparison

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

MetricClaude Opus 4.5Gemini 2.5 FlashComparison
Input / output priceUSD per 1M tokensClaude Opus 4.5$5 input / $25 outputGemini 2.5 Flash$0.3 input / $2.5 outputGemini 2.5 Flash has the lower combined listed price.
Generation speedtokens per secondClaude Opus 4.546 tok/sGemini 2.5 Flash221 tok/sGemini 2.5 Flash has the higher measured throughput.
First-answer latencyseconds to first tokenClaude Opus 4.51.01 sGemini 2.5 Flash0.50 sGemini 2.5 Flash reaches the first token sooner.
Context windowmaximum listed tokensClaude Opus 4.5200KGemini 2.5 Flash1MGemini 2.5 Flash lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
Terminal-Bench 2.0Source 59.3%—Not comparable
OSWorld-VerifiedSource 66.3%—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
τ²-bench resultsSource 86.3%14.9%Claude Opus 4.5 leads
Gert LabsSource 64.23%—Not comparable
JobBenchSource 32.3%—Not comparable
Coding
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
SWE-bench VerifiedSource 80.9%—Not comparable
LiveCodeBench v6Source 84.8%—Not comparable
SWE-bench ProSource 57.1%—Not comparable
SWE MultilingualSource 77.5%—Not comparable
NL2RepoSource 43.2%—Not comparable
AA-SciCodeSource 47.0%29.1%Claude Opus 4.5 leads
Reasoning
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
LongBench v2Source 64.4%—Not comparable
AI-NeedleSource 74%—Not comparable
AA-LCRSource 65.3%45.9%Claude Opus 4.5 leads
CritPtSource 0.3%1.4%Gemini 2.5 Flash leads
Knowledge
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
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
Artificial Analysis Intelligence IndexSource 34.7%14.1%Claude Opus 4.5 leads
AA-GPQA DiamondSource 81.0%68.3%Claude Opus 4.5 leads
AA-HLESource 12.9%5.1%Claude Opus 4.5 leads
AA-Omniscience IndexSource -3.9%-42.0%Claude Opus 4.5 leads
AA-Omniscience AccuracySource 40.7%26.5%Claude Opus 4.5 leads
AA-Omniscience Hallucination RateSource 75.4%93.3%Claude Opus 4.5 leads
AA MMLU-ProSource 88.9%—Not comparable
MathClaude Opus 4.5 wins
BenchmarkClaude Opus 4.5Gemini 2.5 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%4.844%Claude Opus 4.5 leads
FrontierMath v2 (Tier 4)Source 4.167%4.167%Tie
Multilingual
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
MMLU-ProXSource 85.7%—Not comparable
NOVA-63Source 56.7%—Not comparable
Multimodal
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
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%65.5%Claude Opus 4.5 leads
Design Arena WebsiteSource 12771145Claude Opus 4.5 leads
Inst. Following
BenchmarkClaude Opus 4.5Gemini 2.5 FlashResult
IFEvalSource 90.9%—Not comparable
IFBenchSource 58%—Not comparable
AA-IFBenchSource 43.0%39.0%Claude Opus 4.5 leads
Frequently Asked Questions (2)

Which is better, Claude Opus 4.5 or Gemini 2.5 Flash?

Claude Opus 4.5 is ahead on BenchLM's BenchAlign leaderboard, 64.22 to 48.09. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 20.690% and 4.844%.

Which is better for math, Claude Opus 4.5 or Gemini 2.5 Flash?

Claude Opus 4.5 has the edge for math in this comparison, averaging 57.5 versus 4.7. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.

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