Gemini 3.1 Flash Lite Preview vs GPT-5.2 Codex

Gemini 3.1 Flash Lite Preview (2026) and GPT-5.2 Codex (2025) compare a standalone API model against a coding-specialized model. Gemini 3.1 Flash Lite Preview ships a 1M-token context window, while GPT-5.2 Codex ships a not-yet-sourced context window. On pricing, Gemini 3.1 Flash Lite Preview costs $0.25/1M input tokens versus $1.75/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.

Treat this as a product-type comparison: Gemini 3.1 Flash Lite Preview is standalone API model, while GPT-5.2 Codex is coding-specialized model. Choose based on workflow fit before reading any benchmark or price row as decisive.

Decision scorecard

Local evidence first

Signal	Gemini 3.1 Flash Lite Preview	GPT-5.2 Codex	How to read it
Product type	Standalone API model	Coding-specialized model	Read downstream rows through the product-type lens before comparing benchmarks, prices, or provider availability.
Best for	multimodal apps, tool-calling agents, and long-context analysis	custom coding agents, code generation, and tool loops	Use-case synthesis from product type, capability flags, context, and provider data.
Decision fit	Coding, RAG, and Agents	Coding, Agents, and Vision	Primary workload tags from local decision data.
Context window	1M	—	Higher is better when prompts, retrieval chunks, or transcripts are large.
Cheapest output	$1.50/1M tokens	$14/1M tokens	Cheapest tracked provider route; verify your exact region and tier.
Provider routes	4 tracked	1 tracked	Broader coverage can reduce vendor lock-in and fallback risk.
Shared benchmarks	0 rows	0 rows	No shared benchmark rows are sourced for this pair yet.

Decision tradeoffs

Choose Gemini 3.1 Flash Lite Preview when...

Gemini 3.1 Flash Lite Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
Gemini 3.1 Flash Lite Preview has the lower cheapest tracked output price at $1.50/1M tokens.
Gemini 3.1 Flash Lite Preview has broader tracked provider coverage for fallback and procurement flexibility.
Gemini 3.1 Flash Lite Preview uniquely exposes Structured outputs in local model data.
Local decision data tags Gemini 3.1 Flash Lite Preview for Coding, RAG, and Agents.

Choose GPT-5.2 Codex when...

GPT-5.2 Codex uniquely exposes Reasoning in local model data.
Local decision data tags GPT-5.2 Codex for Coding, Agents, and Vision.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate Gemini 3.1 Flash Lite Preview

Requests / monthInput tokens / requestOutput tokens / request

Gemini 3.1 Flash Lite Preview

$575

Cheapest tracked route/tier: Google AI Studio

GPT-5.2 Codex

$4,900

Cheapest tracked route/tier: Vercel AI Gateway

Estimated monthly gap: $4,325. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Gemini 3.1 Flash Lite Preview -> GPT-5.2 Codex

Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
GPT-5.2 Codex is $12.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Check replacement coverage for Structured outputs before moving production traffic.
GPT-5.2 Codex adds Reasoning in local capability data.

GPT-5.2 Codex -> Gemini 3.1 Flash Lite Preview

Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
Gemini 3.1 Flash Lite Preview is $12.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
Check replacement coverage for Reasoning before moving production traffic.
Gemini 3.1 Flash Lite Preview adds Structured outputs in local capability data.

Specs

Specification	Gemini 3.1 Flash Lite Preview Google DeepMind	GPT-5.2 Codex OpenAI
Released	2026-03-03	2025-12-18
Context window	1M	—
Parameters	—	—
Architecture	decoder only	decoder only
License	Proprietary	Proprietary
Knowledge cutoff	2025-01	2025-08

Pricing and availability

Pricing attribute	Gemini 3.1 Flash Lite Preview	GPT-5.2 Codex
Input price	$0.25/1M tokens	$1.75/1M tokens
Output price	$1.50/1M tokens	$14/1M tokens
Providers	Google AI Studio GCP Vertex AI OpenRouter Vercel AI Gateway	Vercel AI Gateway

Capabilities

Capability	Gemini 3.1 Flash Lite Preview	GPT-5.2 Codex
Vision	Yes	Yes
Multimodal	Yes	Yes
Reasoning	No	Yes
Function calling	Yes	Yes
Tool use	Yes	Yes
Structured outputs	Yes	No
Code execution	Yes	Yes
IDE integration	No	No
Computer use	No	No
Parallel agents	No	No

Benchmarks

No shared benchmark rows are currently sourced for this pair.

Deep dive

The capability footprint differs most on reasoning mode: GPT-5.2 Codex and structured outputs: Gemini 3.1 Flash Lite Preview. Both models share vision, multimodal input, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.

For cost, Gemini 3.1 Flash Lite Preview lists $0.25/1M input and $1.50/1M output tokens on the cheapest tracked provider, while GPT-5.2 Codex lists $1.75/1M input and $14/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Flash Lite Preview lower by about $4.80 per million blended tokens. Availability is 4 providers versus 1, so concentration risk also matters.

Choose Gemini 3.1 Flash Lite Preview when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.2 Codex when coding workflow support are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.

FAQ

Which is cheaper, Gemini 3.1 Flash Lite Preview or GPT-5.2 Codex?

Gemini 3.1 Flash Lite Preview is cheaper on tracked token pricing. Gemini 3.1 Flash Lite Preview costs $0.25/1M input and $1.50/1M output tokens. GPT-5.2 Codex costs $1.75/1M input and $14/1M output tokens. Provider discounts or batch pricing can still change the final bill.

Is Gemini 3.1 Flash Lite Preview or GPT-5.2 Codex open source?

Gemini 3.1 Flash Lite Preview is listed under Proprietary. GPT-5.2 Codex is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.

Which is better for vision, Gemini 3.1 Flash Lite Preview or GPT-5.2 Codex?

Both Gemini 3.1 Flash Lite Preview and GPT-5.2 Codex expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.

Which is better for multimodal input, Gemini 3.1 Flash Lite Preview or GPT-5.2 Codex?

Both Gemini 3.1 Flash Lite Preview and GPT-5.2 Codex expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.

Which is better for reasoning mode, Gemini 3.1 Flash Lite Preview or GPT-5.2 Codex?

GPT-5.2 Codex has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.

Where can I run Gemini 3.1 Flash Lite Preview and GPT-5.2 Codex?

Gemini 3.1 Flash Lite Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, and Vercel AI Gateway. GPT-5.2 Codex is available on Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.

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Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.