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Model comparison

Gemini 2.5 Flash vs Gemini 3.1 Pro

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.

48.09/100
Margin
7.2pts
winning →
55.3/100
0 category wins1 category wins

Public leaderboard positions: Gemini 2.5 Flash #130 (Supported); Gemini 3.1 Pro #83 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Gemini 2.5 Flash and Gemini 3.1 Pro share 15 comparable benchmark results. 1 of 8 categories are comparable. 0 results are unique to Gemini 2.5 Flash; 32 to Gemini 3.1 Pro.

Updated July 20, 2026
Shared results
15
Gemini 2.5 Flash only
0
Gemini 3.1 Pro only
32
Comparable categories
1 / 8

Pick Gemini 3.1 Pro if you want the stronger benchmark profile. Gemini 2.5 Flash only becomes the better choice if you want the cheaper token bill.

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

Gemini 3.1 Pro is clearly ahead on the BenchAlign aggregate, 55.3 to 48.09. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Gemini 3.1 Pro's sharpest advantage is in mathematics, where it averages 31.8 against 4.7. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 4.844% to 36.900%.

Gemini 3.1 Pro is also the more expensive model on tokens at $2.00 input / $12.00 output per 1M tokens, versus $0.30 input / $2.50 output per 1M tokens for Gemini 2.5 Flash. That is roughly 4.8x 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 2.5 Flash and Gemini 3.1 Pro
CategoryGemini 2.5 FlashΔGemini 3.1 Pro
MathGemini 2.5 Flash4.7Margin→ 27.1Gemini 3.1 Pro31.8
ReasoningGemini 2.5 FlashNot measuredMarginNo overlapGemini 3.1 Pro77.1
MultimodalGemini 2.5 FlashNot measuredMarginNo overlapGemini 3.1 Pro82.6

Decisive benchmark drivers

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

More
A · Gemini 2.5 FlashB · Gemini 3.1 Pro

  1. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 4.844%B 36.900%
    Winner: Gemini 3.1 ProΔ 32.1
    FrontierMath v2 (Tiers 1-3): Gemini 2.5 Flash scored 4.844%; Gemini 3.1 Pro scored 36.900%. Gemini 3.1 Pro wins this benchmark.

  2. FrontierMath v2 (Tier 4)

    Math
    Source ↗
    A 4.167%B 16.700%
    Winner: Gemini 3.1 ProΔ 12.5
    FrontierMath v2 (Tier 4): Gemini 2.5 Flash scored 4.167%; Gemini 3.1 Pro scored 16.700%. Gemini 3.1 Pro wins this benchmark.

Operational comparison

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

MetricGemini 2.5 FlashGemini 3.1 ProComparison
Input / output priceUSD per 1M tokensGemini 2.5 Flash$0.3 input / $2.5 outputGemini 3.1 Pro$2 input / $12 outputGemini 2.5 Flash has the lower combined listed price.
Generation speedtokens per secondGemini 2.5 Flash221 tok/sGemini 3.1 Pro109 tok/sGemini 2.5 Flash has the higher measured throughput.
First-answer latencyseconds to first tokenGemini 2.5 Flash0.50 sGemini 3.1 Pro29.71 sGemini 2.5 Flash reaches the first token sooner.
Context windowmaximum listed tokensGemini 2.5 Flash1MGemini 3.1 Pro1MListed context windows are equal.

Benchmark Deep Dive

Agentic
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
τ²-bench resultsSource 14.9%95.6%Gemini 3.1 Pro leads
Claw-EvalSource —57.8%Not comparable
DeepSearchQASource —69.7%Not comparable
AA Agentic IndexSource —21.4%Not comparable
APEX-Agents-AASource —32.0%Not comparable
GDPval-AASource —23.2%Not comparable
GDPval-AASource —965Not comparable
Gert LabsSource —56.87%Not comparable
ResearchClawBenchSource —13.3%Not comparable
AA AutomationBenchSource —37.5%Not comparable
AA EnterpriseOps-GymSource —42.2%Not comparable
AA Harvey LABSource —0.0%Not comparable
AA ITBenchSource —30.3%Not comparable
AA Tau3 BankingSource —16.5%Not comparable
terminalBenchHardSource —53.8%Not comparable
aaTerminalBench21Source —73.8%Not comparable
Coding
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
AA-SciCodeSource 29.1%58.9%Gemini 3.1 Pro leads
LiveCodeBench ProSource —82.9%Not comparable
React Native EvalsSource —78.9%Not comparable
Vibe Code BenchSource —32.03%Not comparable
AA Coding IndexSource —68.8%Not comparable
Reasoning
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
AA-LCRSource 45.9%72.7%Gemini 3.1 Pro leads
CritPtSource 1.4%17.7%Gemini 3.1 Pro leads
ARC-AGI-2Source —77.1%Not comparable
Knowledge
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
Artificial Analysis Intelligence IndexSource 14.1%46.5%Gemini 3.1 Pro leads
AA-GPQA DiamondSource 68.3%94.1%Gemini 3.1 Pro leads
AA-HLESource 5.1%44.7%Gemini 3.1 Pro leads
AA-Omniscience IndexSource -42.0%32.9%Gemini 3.1 Pro leads
AA-Omniscience AccuracySource 26.5%55.3%Gemini 3.1 Pro leads
AA-Omniscience Hallucination RateSource 93.3%49.9%Gemini 3.1 Pro leads
GPQA-DSource —94.3%Not comparable
HLE w/o toolsSource —45.4%Not comparable
HealthBench HardSource —20.6%Not comparable
MedXpertQA (Text)Source —71.5%Not comparable
MathGemini 3.1 Pro wins
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
FrontierMath v2 (Tiers 1-3)Source 4.844%36.900%Gemini 3.1 Pro leads
FrontierMath v2 (Tier 4)Source 4.167%16.700%Gemini 3.1 Pro leads
Multilingual
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
AA Global-MMLU-LiteSource —93.2%Not comparable
Multimodal
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
AA-MMMU-ProSource 65.5%82.4%Gemini 3.1 Pro leads
Design Arena WebsiteSource 11481284Gemini 3.1 Pro leads
MMMU-ProSource —83.9%Not comparable
CharXivSource —80.2%Not comparable
ERQASource —69.4%Not comparable
SimpleVQASource —72.4%Not comparable
ScreenSpot ProSource —84.4%Not comparable
ZeroBenchSource —29.0%Not comparable
MedXpertQA (MM)Source —81.3%Not comparable
Inst. Following
BenchmarkGemini 2.5 FlashGemini 3.1 ProResult
AA-IFBenchSource 39.0%77.1%Gemini 3.1 Pro leads
Frequently Asked Questions (2)

Which is better, Gemini 2.5 Flash or Gemini 3.1 Pro?

Gemini 3.1 Pro is ahead on BenchLM's BenchAlign leaderboard, 55.3 to 48.09. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 4.844% and 36.900%.

Which is better for math, Gemini 2.5 Flash or Gemini 3.1 Pro?

Gemini 3.1 Pro has the edge for math in this comparison, averaging 31.8 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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Last updated: July 20, 2026

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