The Known Good Updated 25 Jul 2026
Google: Gemini 2.5 Pro vs Google: Gemini 3.5 Flash ·Google vs Google

Google: Gemini 2.5 Pro vs Google: Gemini 3.5 Flash — head-to-head comparison

Google: Gemini 2.5 Pro profile Google: Gemini 3.5 Flash profile All comparisons
Google: Gemini 2.5 Pro — Google
Quality
#29 of 61
64based on 4 of 6 evaluations
Known Good Index
Speed
#53 of 316
96.5
Output tokens per second
Price
#262 of 340
$3.44
Blended per 1M tokens
In $1.25 · Out $10.00
Cache hit price
#106 of 206
$0.12
per 1M tokens (−90%)
Context
#29 of 345
1.05M
tokens (~1,600 pages)
Google: Gemini 3.5 Flash — Google
Quality
#3 of 61
95based on 3 of 6 evaluations
Known Good Index
Speed
#31 of 316
119.1
Output tokens per second
Price
#257 of 340
$3.38
Blended per 1M tokens
In $1.50 · Out $9.00
Cache hit price
#127 of 206
$0.15
per 1M tokens (−90%)
Context
#46 of 345
1.05M
tokens (~1,600 pages)
Summary

On the Known Good Index, Google: Gemini 2.5 Pro scores 64 and Google: Gemini 3.5 Flash scores 95 — a 31-point lead for Google: Gemini 3.5 Flash. They share 3 published evaluations, with Google: Gemini 2.5 Pro ahead on 0 and Google: Gemini 3.5 Flash ahead on 3.

Blended pricing is $3.44 per 1M tokens for Google: Gemini 2.5 Pro and $3.38 for Google: Gemini 3.5 Flash, within 10% of each other.

Throughput is 96 tokens per second for Google: Gemini 2.5 Pro and 119 for Google: Gemini 3.5 Flash, with time to first token at 5.3s and 1.7s. Google: Gemini 2.5 Pro accepts 1.05M tokens of context against 1.05M.

Google: Gemini 2.5 Pro is proprietary; Google: Gemini 3.5 Flash is proprietary. 2 tracked hosts serve one or both, and 2 serve both.

Generated from tracked data on 26 Jul 2026 · how these comparisons are computed →

At a glance
MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Known Good Index 64 based on 4 of 6 evaluations 95 based on 3 of 6 evaluations
Blended $/1M $3.44 $3.38
Output tok/s 96 119
Context window 1.05M 1.05M
Providers 2 2
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Quality

Known Good Index and the capability indices, side by side

IndicesComponents
Index scores

Each index is min-max normalised across tracked models and scaled 0–100 from published evaluations. We do not run these evaluations.

MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Known Good Index 64 95
Coding Index 42
Mathematics Index 84 96
Science Index 89 98
Agentic Index 42 92
Openness Index 5 5
The Known Good

Quality Breakdown

Every evaluation both models report a published score for

Evaluations both models report

Bar = Google: Gemini 2.5 Pro · marker = Google: Gemini 3.5 Flash · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond85 / 93
MATH / AIME84 / 96
SWE-bench Verified58 / 79

Right-hand figures read Google: Gemini 2.5 Pro / Google: Gemini 3.5 Flash. Google: Gemini 2.5 Pro leads on 0 of 3, Google: Gemini 3.5 Flash on 3.

The Known Good

Arena Elo

Human preference rating from blind pairwise votes

Arena ratings

Elo from blind pairwise votes, ingested from Arena. Higher is better.

MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Text Arena 1,457
Text Arena (style controlled) 1,446
The Known Good

Price & Cost

Published API pricing by token type

Per token typeCache discount
Published pricing

USD per 1M tokens. Blended is a 3:1 input:output mix. Live from OpenRouter, cross-checked against models.dev. Lower is better.

MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Input $/1M $1.25 $1.50
Output $/1M $10.00 $9.00
Blended $/1M $3.44 $3.38
Cache read $/1M $0.125 $0.150
The Known Good
We publish blended price rather than cost-per-task. Cost-per-task requires token counts from an evaluation suite we do not run. Blended price is computed from published rates and is fully reproducible — see the pricing methodology.

Context Window

Maximum input accepted and maximum output emitted

Context and output limits

Provider-declared limits, from metadata via models.dev and OpenRouter. Higher is better.

MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Context window 1.05M 1.05M
Max output tokens 66k 66k
The Known Good

Speed & Latency

Median throughput and time to first token across hosting providers

Output speedTime to first token
Throughput and latency

Medians across all tracked providers, derived from OpenRouter endpoint telemetry.

MetricGoogle: Gemini 2.5 ProGoogle: Gemini 3.5 Flash
Output tokens/s 96 119
Time to first token 5.3s 1.7s
The Known Good

Providers

Which hosts serve each model, and at what price and speed

2 hosts · 2 serve both
Full provider benchmarks →
Provider Google: Gemini 2.5 Pro blendedGoogle: Gemini 2.5 Pro tok/s Google: Gemini 3.5 Flash blendedGoogle: Gemini 3.5 Flash tok/s
Google AI Studio $1.72 106 $1.69 124
Google · first party $1.72 93 $1.69 117

Per-host pricing and telemetry from OpenRouter. A dash means that host does not serve that model.

The Known Good
Sources for this page
Pricing & providers — OpenRouter Metadata — models.dev Benchmarks — Epoch AI (CC-BY 4.0)Elo — Arena Full attribution →