The Known Good Updated 4 Sep 2026 Subscribe
Google: Gemini 3.5 Flash vs OpenAI: o3 Mini ·Google vs OpenAI

Google: Gemini 3.5 Flash vs OpenAI: o3 Mini — head-to-head comparison

Google: Gemini 3.5 Flash profile OpenAI: o3 Mini profile All comparisons
Google: Gemini 3.5 Flash — Google
Quality
#3 of 65
95based on 3 of 7 evaluations
Known Good Index
Speed
#10 of 338
162.0
Output tokens per second
Price
#341 of 442
$3.38
Blended per 1M tokens
In $1.50 · Out $9.00
Cache hit price
#205 of 324
$0.15
per 1M tokens (−90%)
Context
#78 of 476
1.05M
tokens (~1,600 pages)
OpenAI: o3 Mini — OpenAI
Quality
#14 of 65
86based on 4 of 7 evaluations
Known Good Index
Speed
#29 of 338
125.5
Output tokens per second
Price
#302 of 442
$1.93
Blended per 1M tokens
In $1.10 · Out $4.40
Cache hit price
#302 of 324
$0.55
per 1M tokens (−50%)
Context
#306 of 476
200k
tokens (~300 pages)
Summary

On the Known Good Index, Google: Gemini 3.5 Flash scores 95 and OpenAI: o3 Mini scores 86 — a 9-point lead for Google: Gemini 3.5 Flash. They share 2 published evaluations, with Google: Gemini 3.5 Flash ahead on 2 and OpenAI: o3 Mini ahead on 0.

Blended pricing is $3.38 per 1M tokens for Google: Gemini 3.5 Flash and $1.93 for OpenAI: o3 Mini — OpenAI: o3 Mini is about 1.8× cheaper.

Throughput is 162 tokens per second for Google: Gemini 3.5 Flash and 126 for OpenAI: o3 Mini, with time to first token at 2.2s and 2.5s. Google: Gemini 3.5 Flash accepts 1.05M tokens of context against 200k.

Google: Gemini 3.5 Flash is proprietary; OpenAI: o3 Mini is proprietary. 3 tracked hosts serve one or both.

Generated from tracked data on 4 Sep 2026 · how these comparisons are computed →

At a glance
MetricGoogle: Gemini 3.5 FlashOpenAI: o3 Mini
Known Good Index 95 based on 3 of 7 evaluations 86 based on 4 of 7 evaluations
Blended $/1M $3.38 $1.93
Output tok/s 162 126
Context window 1.05M 200k
Providers 2 1
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Quality

Known Good Index and the capability indices, side by side

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 3.5 FlashOpenAI: o3 Mini
Known Good Index 95 86
Mathematics Index — 88
Reasoning Index — 85
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 3.5 Flash · marker = OpenAI: o3 Mini · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond93 / 77
Mock AIME 2024–2596 / 77

Right-hand figures read Google: Gemini 3.5 Flash / OpenAI: o3 Mini. Google: Gemini 3.5 Flash leads on 2 of 2, OpenAI: o3 Mini on 0.

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 3.5 FlashOpenAI: o3 Mini
Text Arena — 1,319
Text Arena (style controlled) — 1,348
The Known Good

Price & Cost

Published API pricing by token type

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 3.5 FlashOpenAI: o3 Mini
Input $/1M $1.50 $1.10
Output $/1M $9.00 $4.40
Blended $/1M $3.38 $1.93
Cache read $/1M $0.150 $0.550
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 3.5 FlashOpenAI: o3 Mini
Context window 1.05M 200k
Max output tokens 66k 100k
The Known Good

Speed & Latency

Mean throughput and time to first token across hosting providers, over successful measurements from the last 48 hours

Throughput and latency

Means across all tracked providers over successful measurements from the last 48 hours, derived from OpenRouter endpoint telemetry.

MetricGoogle: Gemini 3.5 FlashOpenAI: o3 Mini
Output tokens/s 162 126
Time to first token 2.2s 2.5s
The Known Good

Providers

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

3 hosts
Full provider benchmarks →
Provider Google: Gemini 3.5 Flash blendedGoogle: Gemini 3.5 Flash tok/s OpenAI: o3 Mini blendedOpenAI: o3 Mini tok/s
Google AI Studio $1.69 187 — —
Google · first party $1.69 126 — —
OpenAI · first party — — $1.93 201

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 →