Model comparison
GPT-5.1-Codex vs o3-pro
o3-pro is the stronger model overall, scoring 42.9 to 38.6 on the Noometry Index. GPT-5.1-Codex costs 10× less per token, which makes it the better buy when o3-pro's lead doesn't matter for your workload.
Last verified . 0 shared benchmarks.
Summary
- The widest gap is in coding, where o3-pro leads 55.5 to 41.9.
- GPT-5.1-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $20 / $80 for o3-pro.
- GPT-5.1-Codex accepts more context: 400K tokens versus 200K.
Side by side
| GPT-5.1-Codex | o3-pro | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 38.6 | 42.9 |
| Released | 2025-11-12 | 2025-06-10 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 200K |
| Max output | 128K | 100K |
| Input $ / M tokens | $1.25 | $20 |
| Output $ / M tokens | $10 | $80 |
| Results tracked | 6 | 12 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding o3-pro leads
GPT-5.1-Codex: 41.9 (#116), o3-pro: 55.5 (#24)
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| SWE-bench Verified (bash only) | 66% | — |
| Aider Polyglot | — | 84.9% |
| LMArena WebDev | 1337 | — |
| WeirdML | — | 58.2% |
| ALE-Bench | 1,245 | — |
Agentic & Tool Use Not comparable
GPT-5.1-Codex: 38.0 (#33), o3-pro: —
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, o3-pro: 23.8 (#171)
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| ARC-AGI-2 | — | 4.9% |
| Kagi LLM Benchmark | — | 72.1% |
| ARC-AGI-1 | — | 59.3% |
| DTBench | — | 86.9% |
| LMCA | — | 38.5% |
| Epoch Capabilities Index | — | 147.42 |
Math Not comparable
GPT-5.1-Codex: 30.3 (#235), o3-pro: —
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| ProofBench | 9% | — |
Knowledge Not comparable
GPT-5.1-Codex: —, o3-pro: 29.5 (#238)
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| Confabulations | — | 14.2% |
| Vectara Hallucination Rate | — | 23.3% |
Long Context Not comparable
GPT-5.1-Codex: —, o3-pro: 72.2 (#1)
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| Fiction.LiveBench | — | 97.2% |
Writing & Preference Not comparable
GPT-5.1-Codex: —, o3-pro: 57.1 (#133)
| Benchmark | GPT-5.1-Codex | o3-pro |
|---|---|---|
| Short-Story Creative Writing | — | 84.4% |
Frequently asked questions
Is GPT-5.1-Codex better than o3-pro?
o3-pro is the stronger model overall, scoring 42.9 to 38.6 on the Noometry Index. GPT-5.1-Codex costs 10× less per token, which makes it the better buy when o3-pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5.1-Codex or o3-pro?
GPT-5.1-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; o3-pro lists at $20 and $80.
Is GPT-5.1-Codex or o3-pro better for coding?
o3-pro scores higher on coding benchmarks: 55.5 versus 41.9 in the Noometry coding category.
Which has the bigger context window?
GPT-5.1-Codex does, with 400K tokens against 200K.
How many benchmarks do GPT-5.1-Codex and o3-pro share?
0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and o3-pro has 12.