Gemini 3.1 Flash Lite vs GPT-5.1-Codex
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose Gemini 3.1 Flash Lite if you need
- ✓Choose Gemini 3.1 Flash Lite if you need maximum output speed and low latency at 310 t/s.
- ✓Choose Gemini 3.1 Flash Lite if you need the lowest price at $1.5 per million tokens.
- ✓Choose Gemini 3.1 Flash Lite if you need a 1M-token context window plus video support.
- ✓Choose Gemini 3.1 Flash Lite if you need resource-efficient inference for high-volume multimodal workloads.
Choose GPT-5.1-Codex if you need
- ✓Choose GPT-5.1-Codex if you need higher intelligence (43.1 index) for complex tasks.
- ✓Choose GPT-5.1-Codex if you need strong performance on extended coding workflows with visual context.
- ✓Choose GPT-5.1-Codex if you need specialized software-development capabilities.
- ✓Choose GPT-5.1-Codex if you need coherence across very large text-and-image inputs without video.
Verdict
GPT-5.1-Codex leads on raw intelligence (43.1 vs 33.5) and specialized coding performance, while Gemini 3.1 Flash Lite dominates speed (310 t/s vs 178 t/s), price ($1.5 vs $10 per M), and context length (1M vs 400K). Gemini supports video in addition to text and images; GPT-5.1-Codex is restricted to text and images but integrates visual context more effectively for software tasks. The choice hinges on whether efficiency and scale or peak capability and coding depth matter most.
Gemini 3.1 Flash Lite vs GPT-5.1-Codex: side by side
| Spec | Gemini 3.1 Flash Lite | GPT-5.1-Codex | Winner |
|---|---|---|---|
| Intelligence | 33.5 | 43.1 | GPT-5.1-Codex |
| Output speed | 310 t/s | 178 t/s | Gemini 3.1 Flash Lite |
| Output price | $1.50/1M | $10.00/1M | Gemini 3.1 Flash Lite |
| Context | 1049K | 400K | Gemini 3.1 Flash Lite |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | OpenAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5.1-CodexGPT-5.1-Codex scores 43.1 on the intelligence index compared with Gemini 3.1 Flash Lite at 33.5. This gap favors GPT-5.1-Codex on complex reasoning and coding depth, while Gemini's lite design explicitly trades peak capability for speed.
Speed & Cost
Winner: Gemini 3.1 Flash LiteGemini 3.1 Flash Lite delivers 310.24 tokens per second at $1.5 per million tokens versus GPT-5.1-Codex at 178.06 t/s and $10 per million. The facts show clear advantages for Gemini on both latency-sensitive and high-volume use cases.
Context & Modalities
Winner: Gemini 3.1 Flash LiteGemini supports a 1,048,576-token context plus text, image, and video; GPT-5.1-Codex is limited to 400,000 tokens and text-plus-image only. Gemini therefore handles larger multimodal inputs at lower cost, while GPT-5.1-Codex focuses on text-image coherence for coding.
Task Specialization
Winner: GPT-5.1-CodexGPT-5.1-Codex lists explicit strengths in extended coding workflows and visual-code integration. Gemini lists broader but lighter multimodal support without the same coding emphasis, making GPT-5.1-Codex the stronger choice for software-development pipelines.
Gemini 3.1 Flash Lite
Pros
- +High speed and low latency
- +Handles very large context windows
- +Broad modality support in a lightweight package
- +Resource-efficient inference
Cons
- –Reduced depth on highly complex reasoning tasks
- –Lite design trades peak capability for speed
- –May require more guidance on nuanced or creative outputs
GPT-5.1-Codex
Pros
- +Strong performance on extended coding workflows
- +Effective integration of visual context with code
- +Handles very large inputs without losing coherence
- +Specialized for software development tasks
Cons
- –Limited to text and image inputs only
- –High computational cost for maximum context
- –May require careful prompt engineering for complex tasks
Summary: Gemini 3.1 Flash Lite vs GPT-5.1-Codex
Select Gemini 3.1 Flash Lite when speed, cost, and maximum context with video are priorities. Select GPT-5.1-Codex when higher intelligence and coding-specific multimodal performance outweigh the higher price and slower speed. The data show no single winner across all dimensions.
Frequently asked questions
GPT-5.1-Codex is stronger on intelligence and coding specialization; Gemini 3.1 Flash Lite is better on speed, price, and context size. Neither dominates every metric.