Gemini 3.8 Flash vs GPT-5.1 Codex
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
Gemini 3.8 Flash by Google wins on 6 of 6 benchmarks against GPT-5.1 Codex by OpenAI, which leads on 0. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
Coding: In coding, Gemini 3.8 Flash scores 1317 on Design Arena ELO compared to GPT-5.1 Codex's 1197, while Gemini 3.8 Flash scores 1314 on Website Arena ELO compared to GPT-5.1 Codex's 1174.
Context: In context, Gemini 3.8 Flash scores 1.0M on Context Length compared to GPT-5.1 Codex's 400K.
Pricing Comparison
Gemini 3.8 Flash costs $0.75/1M input tokens and $3.8/1M output tokens, while GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output. Gemini 3.8 Flash is the more affordable option for API usage.
Verdict
Gemini 3.8 Flash leads across the board in affordability, making it the stronger overall choice in this comparison.
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Gemini 3.8 Flash vs GPT-5.1 Codex — FAQ
Which is better, Gemini 3.8 Flash or GPT-5.1 Codex?
Gemini 3.8 Flash wins on more benchmarks overall (6 vs 0). However, the best choice depends on your specific needs — each model excels in different areas.
How does Gemini 3.8 Flash compare to GPT-5.1 Codex for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is Gemini 3.8 Flash cheaper than GPT-5.1 Codex?
Yes, Gemini 3.8 Flash is cheaper. Gemini 3.8 Flash costs $0.75/1M input and $3.8/1M output tokens. GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output tokens.
Which is faster, Gemini 3.8 Flash or GPT-5.1 Codex?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the Gemini 3.8 Flash vs GPT-5.1 Codex comparison cover?
This comparison covers 6 benchmarks including Input Cost, Output Cost, Context Length, Cached Input Cost, Design Arena ELO, Website Arena ELO. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.