Standard Compute
Model Comparison 2026

Gemini 3.5 Flash vs GPT-5.3-Codex

Gemini 3.5 Flash
Google · Balanced · Proprietary
$3.75/1M · 1.0M ctx
GPT-5.3-Codex
OpenAI · Balanced · Proprietary
$5.42/1M · 400K ctx

Community Vote

Pick a winner in each dimension — change your vote anytime.

Output Quality
Correctness and depth of what it produces
Agentic Ability
Tool calls, instruction-following, and multi-step tasks
Speed
Tokens per second and time-to-first-token
Value for $
How much capability you get per dollar
Reliability
Consistent results — fewer refusals, loops, and format breaks

Specs & Pricing, Side by Side

Spec
Gemini 3.5 Flash
GPT-5.3-Codex
Maker
Google
OpenAI
Blended price / 1M
$3.75
$5.42
Input / output
$1.50 in · $9.00 out / 1M tokens
$1.75 in · $14 out / 1M tokens
Context window
1.0M
400K
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
8.9
8.8
Agentic Ability
8.9
9.3
Speed
9.4
7.8
Value for $
8.7
7.8
Reliability
8.9
8.7

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Gemini 3.5 Flash or GPT-5.3-Codex?

Updated 2026-08-02

Choose Gemini 3.5 Flash if you want high-throughput agents that need big context cheaply. Choose GPT-5.3-Codex if you want codex CLI users and dedicated coding agents.

In our editorial scoring, Gemini 3.5 Flash leads in 4 of five dimensions (output quality, speed, value for $ and reliability), while GPT-5.3-Codex leads in 1. On price, Gemini 3.5 Flash runs about $3.75 per 1M tokens (blended) and is proprietary; GPT-5.3-Codex is about $5.42 and proprietary.

Where Gemini 3.5 Flash falls short
  • Below Pro on hard reasoning
  • Occasional verbosity
Full Gemini 3.5 Flash breakdown →
Where GPT-5.3-Codex falls short
  • Narrower than a general flagship outside coding
  • Mid-tier pricing
Full GPT-5.3-Codex breakdown →

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