GPT-5.1 Codex vs Gemini 3 Pro for coding
Gemini 3 Pro is the stronger coder of the two on benchmarks, but GPT-5.1 Codex can be the better pick when cost, speed, or context window matter more. Below: a side-by-side spec table and exactly when to pick each.
At a glance
| Spec | GPT-5.1 Codex | Gemini 3 Pro |
|---|---|---|
| Provider | OpenAI | |
| Released | Nov 2025 | Nov 2025 |
| SWE-bench Verified | 75% | 76% |
| HumanEval | 95% | 95% |
| MMLU | 88% | 92% |
| Context window | 400K | 1M+ |
| Max output | 128K | 64K |
| Input price (per 1M) | $1.25 | $2 |
| Output price (per 1M) | $10 | $12 |
| Price tier | Mid | Premium |
| Speed | Medium | Medium |
| Hosting | Closed/API | Closed/API |
| Modality | Text + Vision | Multimodal (vision, audio, video) |
| Knowledge cutoff | Oct 2025 | Jan 2026 |
Pick GPT-5.1 Codex if…
- It's cheaper (Mid tier vs Premium).
- It's tuned for codex CLI and long-horizon coding agents; engineered for terminal-driven workflows.
Pick Gemini 3 Pro if…
- It scores higher on SWE-bench Verified (76% vs 75%), the best proxy for real-world coding.
- It has a larger context window (1M+ vs 400K).
- It's tuned for long-horizon agentic tasks, generative UI, multi-modal reasoning, Antigravity-driven workflows.
GPT-5.1 Codex vs Gemini 3 Pro: which is better for coding?
Gemini 3 Pro is the stronger coder of the two on benchmarks, but GPT-5.1 Codex can be the better pick when cost, speed, or context window matter more. See the full spec table for SWE-bench, HumanEval, MMLU, context window, and pricing on both. Benchmarks are a directional signal, not a guarantee for your codebase — the most reliable test is running both on a real task you care about.
Compare these head-to-head with live data, or build a full stack around your pick — Flowpicker shows compatibility and monthly cost.
Open the live comparison →More comparisons
See the full model leaderboard ranked by SWE-bench, HumanEval, and MMLU.