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Model comparison

Gemini 3.5 Flash vs GPT-5.5

Data verified

Head-to-head evidence from 39 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

64.75/100
Margin
8.8pts
winning →
GPT-5.5
OpenAI
73.51/100
1 category wins5 category wins

Public leaderboard positions: Gemini 3.5 Flash #33 (Estimated); GPT-5.5 #9 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Gemini 3.5 Flash and GPT-5.5 share 39 comparable benchmark results. 6 of 8 categories are comparable. 7 results are unique to Gemini 3.5 Flash; 18 to GPT-5.5.

Updated July 23, 2026
Shared results
39
Gemini 3.5 Flash only
7
GPT-5.5 only
18
Comparable categories
6 / 8

Pick GPT-5.5 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 39 shared benchmark results across 7 evidence categories; 6 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

GPT-5.5 is clearly ahead on the BenchAlign aggregate, 73.51 to 64.75. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.5's sharpest advantage is in mathematics, where it averages 47.6 against 32.9. The single biggest benchmark swing on the page is FrontierMath v2 (Tier 4), 14.583% to 35.400%. 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.

GPT-5.5 is also the more expensive model on tokens at $5.00 input / $30.00 output per 1M tokens, versus $1.50 input / $9.00 output per 1M tokens for Gemini 3.5 Flash. That is roughly 3.3x on output cost alone.

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 Gemini 3.5 Flash and GPT-5.5
CategoryGemini 3.5 FlashΔGPT-5.5
MathGemini 3.5 Flash32.9Margin→ 14.7GPT-5.547.6
MultimodalGemini 3.5 Flash83.8Margin← 13.4GPT-5.570.4
KnowledgeGemini 3.5 Flash47.2Margin→ 10.6GPT-5.557.8
ReasoningGemini 3.5 Flash74.7Margin→ 10.3GPT-5.585.0
CodingGemini 3.5 Flash53.9Margin→ 4.7GPT-5.558.6
AgenticGemini 3.5 Flash77.2Margin→ 4.4GPT-5.581.6
Inst. FollowingGemini 3.5 Flash76.3MarginNo overlapGPT-5.5Not measured

Decisive benchmark drivers

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

More
A · Gemini 3.5 FlashB · GPT-5.5

  1. FrontierMath v2 (Tier 4)

    Math
    Source ↗
    A 14.583%B 35.400%
    Winner: GPT-5.5Δ 20.8
    FrontierMath v2 (Tier 4): Gemini 3.5 Flash scored 14.583%; GPT-5.5 scored 35.400%. GPT-5.5 wins this benchmark.

  2. ARC-AGI-2

    Reasoning
    Source ↗
    A 72.1%B 85%
    Winner: GPT-5.5Δ 12.9
    ARC-AGI-2: Gemini 3.5 Flash scored 72.1%; GPT-5.5 scored 85%. GPT-5.5 wins this benchmark.

  3. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 38.966%B 51.700%
    Winner: GPT-5.5Δ 12.7
    FrontierMath v2 (Tiers 1-3): Gemini 3.5 Flash scored 38.966%; GPT-5.5 scored 51.700%. GPT-5.5 wins this benchmark.

  4. HLE

    Knowledge
    Source ↗
    A 40.2%B 52.2%
    Winner: GPT-5.5Δ 12
    HLE: Gemini 3.5 Flash scored 40.2%; GPT-5.5 scored 52.2%. GPT-5.5 wins this benchmark.

  5. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 76.2%B 82%
    Winner: GPT-5.5Δ 5.8
    Terminal-Bench 2.0: Gemini 3.5 Flash scored 76.2%; GPT-5.5 scored 82%. GPT-5.5 wins this benchmark.

Operational comparison

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

MetricGemini 3.5 FlashGPT-5.5Comparison
Input / output priceUSD per 1M tokensGemini 3.5 Flash$1.5 input / $9 outputGPT-5.5$5 input / $30 outputGemini 3.5 Flash has the lower combined listed price.
Generation speedtokens per secondGemini 3.5 Flash284.2 tok/sGPT-5.5Not availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenGemini 3.5 Flash18.55 sGPT-5.5Not availableA complete latency comparison is not available.
Context windowmaximum listed tokensGemini 3.5 Flash1MGPT-5.51MListed context windows are equal.

Benchmark Deep Dive

AgenticGPT-5.5 wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
Terminal-Bench 2.0Source 76.2%82%GPT-5.5 leads
MCP AtlasSource 83.6%75.3%Gemini 3.5 Flash leads
ToolathlonSource 56.5%55.6%Gemini 3.5 Flash leads
OSWorld-VerifiedSource 78.4%78.7%GPT-5.5 leads
Finance Agent v2Source 57.9%—Not comparable
GDPval-AASource 13491490GPT-5.5 leads
τ²-bench resultsSource 95.3%93.9%Gemini 3.5 Flash leads
GDPval-AASource 42.4%49.5%GPT-5.5 leads
AA Agentic IndexSource 37.5%44.9%GPT-5.5 leads
APEX-Agents-AASource 47.1%37.7%Gemini 3.5 Flash leads
Gert LabsSource 61.85%72.93%GPT-5.5 leads
ResearchClawBenchSource 18.0%17.0%Gemini 3.5 Flash leads
AA AutomationBenchSource 42.6%42.1%Gemini 3.5 Flash leads
AA EnterpriseOps-GymSource 50.1%46.6%Gemini 3.5 Flash leads
terminalBenchHardSource 40.9%60.6%GPT-5.5 leads
CyberGymSource —81.8%Not comparable
BrowseCompSource —84.4%Not comparable
OSWorld 2.0Source —13.0%Not comparable
JobBenchSource —42.7%Not comparable
ExploitGymSource —13.4%Not comparable
AA BriefcaseSource —1154Not comparable
AA Harvey LABSource —86.3%Not comparable
AA ITBenchSource —45.8%Not comparable
AA Tau3 BankingSource —31.3%Not comparable
aaTerminalBench21Source —84.3%Not comparable
CodingGPT-5.5 wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
Terminal-Bench 2.0Source 76.2%82.0%GPT-5.5 leads
SWE-bench ProSource 55.1%58.6%GPT-5.5 leads
SciCodeSource 53.1%—Not comparable
Vibe Code BenchSource 48.68%69.85%GPT-5.5 leads
cursorBench31Source 49.8%59.2%GPT-5.5 leads
cursorBench32Source 48.8%58.4%GPT-5.5 leads
AA Coding IndexSource 70.1%74.9%GPT-5.5 leads
AA-SciCodeSource 53.1%56.1%GPT-5.5 leads
React Native EvalsSource —84.7%Not comparable
FrontierCode 1.1 MainSource —43.0%Not comparable
ReasoningGPT-5.5 wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
MRCRv2Source 77.3%—Not comparable
MRCR 1MSource 26.6%—Not comparable
ARC-AGI-2Source 72.1%85%GPT-5.5 leads
AA-LCRSource 69.3%74.3%GPT-5.5 leads
CritPtSource 13.1%27.1%GPT-5.5 leads
MRCR v2 64K-128KSource —83.1%Not comparable
MRCR v2 128K-256KSource —87.5%Not comparable
KnowledgeGPT-5.5 wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
Artificial Analysis Intelligence IndexSource 50.2%54.8%GPT-5.5 leads
GPQASource 92.2%93.6%GPT-5.5 leads
GPQA-DSource 92.7%93.6%GPT-5.5 leads
HLESource 40.2%52.2%GPT-5.5 leads
AA-Omniscience AccuracySource 51.9%56.9%GPT-5.5 leads
AA-Omniscience Hallucination RateSource 60.7%85.5%Gemini 3.5 Flash leads
AA-GPQA DiamondSource 92.2%93.5%GPT-5.5 leads
AA-HLESource 41.0%44.3%GPT-5.5 leads
AA-Omniscience IndexSource 22.7%20.1%Gemini 3.5 Flash leads
HLE w/o toolsSource —41.4%Not comparable
MathGPT-5.5 wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
FrontierMath v2 (Tiers 1-3)Source 38.966%51.700%GPT-5.5 leads
FrontierMath v2 (Tier 4)Source 14.583%35.400%GPT-5.5 leads
FrontierMath (legacy)Source —51.7%Not comparable
MultimodalGemini 3.5 Flash wins
BenchmarkGemini 3.5 FlashGPT-5.5Result
CharXivSource 84.2%—Not comparable
MMMU-ProSource 83.6%81.2%Gemini 3.5 Flash leads
Blueprint-Bench 2Source 33.6%—Not comparable
AA-MMMU-ProSource 84.3%79.9%Gemini 3.5 Flash leads
Design Arena WebsiteSource 12851282Gemini 3.5 Flash leads
MMMU-Pro w/ PythonSource —83.2%Not comparable
OfficeQA ProSource —54.1%Not comparable
Inst. Following
BenchmarkGemini 3.5 FlashGPT-5.5Result
IFBenchSource 76.3%—Not comparable
AA-IFBenchSource 76.3%75.9%Gemini 3.5 Flash leads
Frequently Asked Questions (7)

Which is better, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 is ahead on BenchLM's BenchAlign leaderboard, 73.51 to 64.75. The biggest single separator in this matchup is FrontierMath v2 (Tier 4), where the scores are 14.583% and 35.400%.

Which is better for knowledge tasks, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 has the edge for knowledge tasks in this comparison, averaging 57.8 versus 47.2. Inside this category, AA-Omniscience Hallucination Rate is the benchmark that creates the most daylight between them.

Which is better for coding, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 has the edge for coding in this comparison, averaging 58.6 versus 53.9. Inside this category, Vibe Code Bench is the benchmark that creates the most daylight between them.

Which is better for math, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 has the edge for math in this comparison, averaging 47.6 versus 32.9. Inside this category, FrontierMath v2 (Tier 4) is the benchmark that creates the most daylight between them.

Which is better for reasoning, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 has the edge for reasoning in this comparison, averaging 85 versus 74.7. Inside this category, CritPt is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Gemini 3.5 Flash or GPT-5.5?

GPT-5.5 has the edge for agentic tasks in this comparison, averaging 81.6 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, Gemini 3.5 Flash or GPT-5.5?

Gemini 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 83.8 versus 70.4. Inside this category, AA-MMMU-Pro is the benchmark that creates the most daylight between them.

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