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Gemini 3.5 Flash vs GPT 5 Codex

At a glance
GoogleGemini 3.5 Flash

Google's high-speed thinking model for agentic workflows, chat, and coding.

861.0M ctx$1.50/$9.00 per M#11/92
OpenAIGPT 5 Codex

GPT-5 optimized for code generation and software engineering tasks.

400K ctx$1.25/$10.00 per M
AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
GoogleGemini 3.5 Flash
Reasoning
AgenticInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Cheaper
Capability
CapabilityECI86.2
Reasoning & Knowledge
Graduate Science92.8%Factual Recall68.4%
Math
Competition Math95.6%Research Math39.0%
Coding
Real-World Coding79.3%
Agentic
Terminal Tasks—Novel Reasoning72.1%
OpenAIGPT 5 Codex
Reasoning
CodingInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:Epoch AI·OpenRouter· as of 2026-07-10
Capability
Capability—
Reasoning & Knowledge
Graduate Science—Factual Recall—
Math
Competition Math—Research Math—
Coding
Real-World Coding—
Agentic
Terminal Tasks44.3%Novel Reasoning—
Specs
GoogleGemini 3.5 Flash
1.0M
Context
66K
Max output
May 2026
Released
OpenAIGPT 5 Codex
400K
Context
128K
Max output
Sep 2025
Released
Capabilities
GoogleGemini 3.5 Flash
Vision
Audio
Reasoning
OpenAIGPT 5 Codex
Vision
Audio
Reasoning
Pricing
GoogleGemini 3.5 Flash
Live pricing, shown before you run
Input$1.50/M tokens
Output$9.00/M tokens
Reasoning$9.00/M tokens
Cache read$0.15/M tokens
Cache write$0.08/M tokens
Image input$1.50/M tokens
Audio input$3.00/M tokens
Web search$0.01/search
OpenAIGPT 5 Codex
Live pricing, shown before you run
Input$1.25/M tokens
Output$10.00/M tokens
Cache read$0.13/M tokens
Web search$0.01/search
Chat with Gemini 3.5 FlashGo to model
Chat with GPT 5 CodexGo to model
Frequently Asked Questions: Gemini 3.5 Flash vs GPT 5 Codex▼

Which is better, Gemini 3.5 Flash or GPT 5 Codex?

▼

Both Gemini 3.5 Flash and GPT 5 Codex are capable AI models. The best choice depends on your specific use case: consider pricing, context window, speed, and which capabilities (vision, reasoning, audio) you need.

Which is cheaper, Gemini 3.5 Flash or GPT 5 Codex?

▼

Gemini 3.5 Flash has a lower blended cost. Gemini 3.5 Flash: $1.50 input / $9.00 output. GPT 5 Codex: $1.25 input / $10.00 output.

Which has a larger context window, Gemini 3.5 Flash or GPT 5 Codex?

▼

Gemini 3.5 Flash has a larger context window: Gemini 3.5 Flash supports 1M tokens vs GPT 5 Codex at 400K tokens.

Do both Gemini 3.5 Flash and GPT 5 Codex support vision?

▼

Yes, both Gemini 3.5 Flash and GPT 5 Codex support vision/image input.

What are the key differences between Gemini 3.5 Flash and GPT 5 Codex?

▼

Gemini 3.5 Flash and GPT 5 Codex have similar overall capabilities. The main differences lie in pricing, context window size, and provider-specific strengths. Use this comparison page to review all metrics side by side.

Which model should I choose for my use case?

▼

If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Gemini 3.5 Flash and GPT 5 Codex for free on idapt.app to see which performs better for your specific needs.

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