The Known Good Updated 25 Jul 2026
Google: Gemini 3.5 Flash vs OpenAI: GPT-5.4 ·Google vs OpenAI

Google: Gemini 3.5 Flash vs OpenAI: GPT-5.4 — head-to-head comparison

Google: Gemini 3.5 Flash profile OpenAI: GPT-5.4 profile All comparisons
Google: Gemini 3.5 Flash — Google
Quality
#3 of 61
95based on 3 of 6 evaluations
Known Good Index
Speed
#31 of 316
119.0
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)
OpenAI: GPT-5.4 — OpenAI
Quality
#10 of 61
90based on 5 of 6 evaluations
Known Good Index
Speed
#78 of 316
82.3
Output tokens per second
Price
#299 of 340
$5.62
Blended per 1M tokens
In $2.50 · Out $15.00
Cache hit price
#160 of 206
$0.25
per 1M tokens (−90%)
Context
#15 of 345
1.05M
tokens (~1,600 pages)
Summary

On the Known Good Index, Google: Gemini 3.5 Flash scores 95 and OpenAI: GPT-5.4 scores 90 — a 6-point lead for Google: Gemini 3.5 Flash. They share 3 published evaluations, with Google: Gemini 3.5 Flash ahead on 2 and OpenAI: GPT-5.4 ahead on 1.

Blended pricing is $3.38 per 1M tokens for Google: Gemini 3.5 Flash and $5.62 for OpenAI: GPT-5.4 — Google: Gemini 3.5 Flash is about 1.7× cheaper.

Throughput is 119 tokens per second for Google: Gemini 3.5 Flash and 82 for OpenAI: GPT-5.4, with time to first token at 1.7s and 2.1s. Google: Gemini 3.5 Flash accepts 1.05M tokens of context against 1.05M.

Google: Gemini 3.5 Flash is proprietary; OpenAI: GPT-5.4 is proprietary. 4 tracked hosts serve one or both.

Generated from tracked data on 25 Jul 2026 · how these comparisons are computed →

At a glance
MetricGoogle: Gemini 3.5 FlashOpenAI: GPT-5.4
Known Good Index 95 based on 3 of 6 evaluations 90 based on 5 of 6 evaluations
Blended $/1M $3.38 $5.62
Output tok/s 119 82
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 3.5 FlashOpenAI: GPT-5.4
Known Good Index 95 90
Coding Index — 89
Mathematics Index 96 95
Science Index 98 98
Reasoning Index — 88
Agentic Index 92 89
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: GPT-5.4 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond93 / 93
MATH / AIME96 / 95
SWE-bench Verified79 / 77

Right-hand figures read Google: Gemini 3.5 Flash / OpenAI: GPT-5.4. Google: Gemini 3.5 Flash leads on 2 of 3, OpenAI: GPT-5.4 on 1.

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: GPT-5.4
Text Arena — 1,453
Text Arena (style controlled) — 1,466
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 3.5 FlashOpenAI: GPT-5.4
Input $/1M $1.50 $2.50
Output $/1M $9.00 $15.00
Blended $/1M $3.38 $5.62
Cache read $/1M $0.150 $0.250
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: GPT-5.4
Context window 1.05M 1.05M
Max output tokens 66k 128k
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 3.5 FlashOpenAI: GPT-5.4
Output tokens/s 119 82
Time to first token 1.7s 2.1s
The Known Good

Providers

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

4 hosts
Full provider benchmarks →
Provider Google: Gemini 3.5 Flash blendedGoogle: Gemini 3.5 Flash tok/s OpenAI: GPT-5.4 blendedOpenAI: GPT-5.4 tok/s
Google AI Studio $1.69 205 — —
Google · first party $1.69 121 — —
Azure · first party — — $5.62 79
OpenAI · first party — — $2.81 68

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 →