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Gemini 3.5 Flash vs GPT-5.3-Codex

Gemini 3.5 Flash leads in 3 of 8 categories

Arena ELO

Tie

Cheaper

Gemini 3.5 Flash

Faster

Tie

Detailed Comparison

CategoryGemini 3.5 FlashGPT-5.3-Codex
ProviderGoogle OpenAI
Context Window1M WIN128K
Input Price ($/1M)$1.5 WIN$1.75
Output Price ($/1M)$9 WIN$14
Arena ELON/A N/A
CodingN/A N/A
ReasoningN/A N/A
Speed (tokens/sec)N/A N/A
Open SourceNo No

Frequently Asked Questions

Which is cheaper, Gemini 3.5 Flash or GPT-5.3-Codex?

Gemini 3.5 Flash is approximately 33% cheaper than GPT-5.3-Codex per million tokens.

Which has a larger context window?

Gemini 3.5 Flash supports 1M context, while GPT-5.3-Codex supports 128K.

Is Gemini 3.5 Flash or GPT-5.3-Codex open source?

Gemini 3.5 Flash is proprietary. GPT-5.3-Codex is proprietary.