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Model comparison

Gemini 2.5 Flash vs o1

Data verified

Head-to-head evidence from 12 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

48.09/100
Margin
0.0pts
winning →
o1
OpenAI
48.1/100
0 category wins1 category wins

Public leaderboard positions: Gemini 2.5 Flash #130 (Supported); o1 #129 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Gemini 2.5 Flash and o1 share 12 comparable benchmark results. 1 of 8 categories are comparable. 3 results are unique to Gemini 2.5 Flash; 4 to o1.

Updated July 23, 2026
Shared results
12
Gemini 2.5 Flash only
3
o1 only
4
Comparable categories
1 / 8

Pick o1 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 12 shared benchmark results across 6 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

o1 has the cleaner BenchAlign overall profile here, landing at 48.1 versus 48.09. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

o1's sharpest advantage is in mathematics, where it averages 9.3 against 4.7. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 4.844% to 9.310%.

o1 is also the more expensive model on tokens at $15.00 input / $60.00 output per 1M tokens, versus $0.30 input / $2.50 output per 1M tokens for Gemini 2.5 Flash. That is roughly 24.0x on output cost alone. o1 is the reasoning model in the pair, while Gemini 2.5 Flash 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 2.5 Flash gives you the larger context window at 1M, compared with 200K for o1.

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 o1
CategoryGemini 2.5 FlashΔo1
MathGemini 2.5 Flash4.7Margin→ 4.6o19.3
KnowledgeGemini 2.5 FlashNot measuredMarginNo overlapo175.7
Inst. FollowingGemini 2.5 FlashNot measuredMarginNo overlapo192.2

Decisive benchmark drivers

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

More
A · Gemini 2.5 FlashB · o1

  1. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 4.844%B 9.310%
    Winner: o1Δ 4.5
    FrontierMath v2 (Tiers 1-3): Gemini 2.5 Flash scored 4.844%; o1 scored 9.310%. o1 wins this benchmark.

Operational comparison

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

MetricGemini 2.5 Flasho1Comparison
Input / output priceUSD per 1M tokensGemini 2.5 Flash$0.3 input / $2.5 outputo1$15 input / $60 outputGemini 2.5 Flash has the lower combined listed price.
Generation speedtokens per secondGemini 2.5 Flash221 tok/so198 tok/sGemini 2.5 Flash has the higher measured throughput.
First-answer latencyseconds to first tokenGemini 2.5 Flash0.50 so132.29 sGemini 2.5 Flash reaches the first token sooner.
Context windowmaximum listed tokensGemini 2.5 Flash1Mo1200KGemini 2.5 Flash lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkGemini 2.5 Flasho1Result
τ²-bench resultsSource 14.9%62.6%o1 leads
Coding
BenchmarkGemini 2.5 Flasho1Result
AA-SciCodeSource 29.1%35.8%o1 leads
AA Coding IndexSource —39.7%Not comparable
Reasoning
BenchmarkGemini 2.5 Flasho1Result
AA-LCRSource 45.9%59.3%o1 leads
CritPtSource 1.4%0.3%Gemini 2.5 Flash leads
Knowledge
BenchmarkGemini 2.5 Flasho1Result
Artificial Analysis Intelligence IndexSource 14.1%23.4%o1 leads
AA-GPQA DiamondSource 68.3%74.7%o1 leads
AA-HLESource 5.1%7.7%o1 leads
AA-Omniscience IndexSource -42.0%-10.5%o1 leads
AA-Omniscience AccuracySource 26.5%34.7%o1 leads
AA-Omniscience Hallucination RateSource 93.3%69.3%o1 leads
MMLUSource —91.8%Not comparable
GPQASource —75.7%Not comparable
Matho1 wins
BenchmarkGemini 2.5 Flasho1Result
FrontierMath v2 (Tiers 1-3)Source 4.844%9.310%o1 leads
FrontierMath v2 (Tier 4)Source 4.167%—Not comparable
Multimodal
BenchmarkGemini 2.5 Flasho1Result
AA-MMMU-ProSource 65.5%—Not comparable
Design Arena WebsiteSource 1145—Not comparable
Inst. Following
BenchmarkGemini 2.5 Flasho1Result
AA-IFBenchSource 39.0%70.3%o1 leads
IFEvalSource —92.2%Not comparable
Frequently Asked Questions (2)

Which is better, Gemini 2.5 Flash or o1?

o1 is ahead on BenchLM's BenchAlign leaderboard, 48.1 to 48.09. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 4.844% and 9.310%.

Which is better for math, Gemini 2.5 Flash or o1?

o1 has the edge for math in this comparison, averaging 9.3 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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