Gemini 3.1 Flash Lite vs GPT-5 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
- ✓high intelligence (44.6) and strong coding specialization
- ✓unified text and image reasoning on large inputs
- ✓maximum context handling up to 400k tokens despite higher cost
Choose GPT-5 Codex if you need
- ✓maximum output speed (310.24 t/s) and low latency
- ✓lowest price ($1.5/M) with 1M token context
- ✓broad text-image-video support in a resource-efficient package
Verdict
GPT-5 Codex leads on intelligence (44.6 index) and coding specialization with unified text-image reasoning, while Gemini 3.1 Flash Lite dominates on speed (310.24 t/s), price ($1.5/M), and context size (1M tokens). GPT-5 Codex suits demanding multimodal coding tasks; Gemini 3.1 Flash Lite prioritizes efficiency and scale for lighter workloads.
Gemini 3.1 Flash Lite vs GPT-5 Codex: side by side
| Spec | Gemini 3.1 Flash Lite | GPT-5 Codex | Winner |
|---|---|---|---|
| Intelligence | 33.5 | 44.6 | GPT-5 Codex |
| Output speed | 310 t/s | 150 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 CodexGPT-5 Codex scores 44.6 on the intelligence index versus 33.5 for Gemini 3.1 Flash Lite. This gap favors Codex for complex reasoning and coding tasks. Gemini's lite design explicitly reduces depth on highly complex problems.
Speed
Winner: Gemini 3.1 Flash LiteGemini 3.1 Flash Lite outputs at 310.24 t/s compared to 149.9 t/s for GPT-5 Codex. Its lightweight architecture delivers high speed and low latency. Codex faces higher resource demands that can slow very long outputs.
Pricing & Context
Winner: Gemini 3.1 Flash LiteGemini costs $1.5 per million tokens versus $10 for GPT-5 Codex while offering a 1M token context window against 400k. These advantages make Gemini far more scalable for large inputs. Codex's higher price aligns with its stronger peak capability.
Modality Support
Winner: Gemini 3.1 Flash LiteGemini 3.1 Flash Lite supports text, image, and video in one lightweight model. GPT-5 Codex is limited to text and static images. Both remain proprietary with unknown parameter counts.
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 Codex
Pros
- +Handles extremely large inputs effectively
- +Strong coding specialization
- +Unified text and image reasoning
Cons
- –High resource demands with maximum context
- –Limited to text and static images
- –Potential coherence loss in very long outputs
Summary: Gemini 3.1 Flash Lite vs GPT-5 Codex
Choose GPT-5 Codex when intelligence and coding depth matter most despite higher cost and slower speed. Select Gemini 3.1 Flash Lite for speed, price, and broad efficient multimodal handling. The choice hinges on whether peak reasoning or operational efficiency is the priority.
Frequently asked questions
GPT-5 Codex is stronger on intelligence and coding tasks while Gemini 3.1 Flash Lite is better for speed, cost, and scale; neither is universally superior.