GPT-5.1 vs o3 for coding
GPT-5.1 is the stronger coder of the two on benchmarks, but o3 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 | o3 |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Released | Nov 2025 | Apr 2025 |
| SWE-bench Verified | 76% | 71% |
| HumanEval | 95% | 96% |
| MMLU | 89% | 91% |
| Context window | 400K | 200K |
| Max output | 128K | 100K |
| Input price (per 1M) | $1.25 | $10 |
| Output price (per 1M) | $10 | $40 |
| Price tier | Mid | Premium |
| Speed | Medium | Slow/Reasoning |
| Hosting | Closed/API | Closed/API |
| Modality | Multimodal (vision) | Multimodal (vision) |
| Knowledge cutoff | Oct 2025 | Jun 2024 |
Pick GPT-5.1 if…
- It scores higher on SWE-bench Verified (76% vs 71%), the best proxy for real-world coding.
- It's cheaper (Mid tier vs Premium).
- It has a larger context window (400K vs 200K).
- It responds faster (Medium).
Pick o3 if…
- It's tuned for hardest coding problems, complex multi-step reasoning, advanced debugging.
GPT-5.1 vs o3: which is better for coding?
GPT-5.1 is the stronger coder of the two on benchmarks, but o3 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.
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See the full model leaderboard ranked by SWE-bench, HumanEval, and MMLU.