# Gemini 3.8 Live Extended Thinking vs GPT-5.1-Codex

> Side-by-side benchmark comparison for Gemini 3.8 Live Extended Thinking and GPT-5.1-Codex across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gemini-3-8-live-extended-thinking-vs-gpt-5-1-codex
- Last updated: September 15, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Gemini 3.8 Live Extended Thinking and GPT-5.1-Codex.

## Summary

- Gemini 3.8 Live Extended Thinking and GPT-5.1-Codex do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Gemini 3.8 Live Extended Thinking | GPT-5.1-Codex |
|----------|----------|----------|
| Creator | Google | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 400K |
| Independent public score (not head-to-head) | null | 48.1 |
| Benchmarks Covered | 0 | 3 |
| Pricing (input/output) | $0.75 / $4.50 | $1.25 / $10.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 48.8 (Estimated · #64/153)

| Benchmark | Gemini 3.8 Live Extended Thinking | GPT-5.1-Codex | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | Coming soon | 49.68% | Coming soon |
| JobBench | Coming soon | 26.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 44.9 (Estimated · #92/152)

| Benchmark | Gemini 3.8 Live Extended Thinking | GPT-5.1-Codex | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | Coming soon | 13.12% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 66.8 (Unranked · 1 rankable row)

### Reasoning

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 68.6 (Unranked · 2 rankable rows)

### Knowledge

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 51.7 (Estimated · #70/183)

### Instruction Following

- Winner: Insufficient shared evidence
- Gemini 3.8 Live Extended Thinking public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 85.6 (#42/123)

## FAQ

### Can I compare Gemini 3.8 Live Extended Thinking and GPT-5.1-Codex on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Gemini 3.8 Live Extended Thinking vs Gemini 3.8 Live](/compare/gemini-3-8-live-vs-gemini-3-8-live-extended-thinking)
- [GPT-5.1-Codex vs Gemini 3.8 Live](/compare/gemini-3-8-live-vs-gpt-5-1-codex)
- [Gemini 3.8 Live Extended Thinking vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gemini-3-8-live-extended-thinking)
- [GPT-5.1-Codex vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-5-1-codex)

## Explore More

- [Gemini 3.8 Live Extended Thinking profile](/models/gemini-3-8-live-extended-thinking)
- [GPT-5.1-Codex profile](/models/gpt-5-1-codex)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)