Model comparison
GPT-5.1-Codex vs GPT-5 Pro
GPT-5 Pro is the stronger model overall, scoring 46.4 to 38.6 on the Noometry Index. GPT-5.1-Codex costs 12× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.
Last verified . 0 shared benchmarks.
Summary
- The widest gap is in math, where GPT-5 Pro leads 48.5 to 30.3.
- GPT-5.1-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $15 / $120 for GPT-5 Pro.
Side by side
| GPT-5.1-Codex | GPT-5 Pro | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 38.6 | 46.4 |
| Released | 2025-11-12 | 2025-10-06 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 400K |
| Max output | 128K | 272K |
| Input $ / M tokens | $1.25 | $15 |
| Output $ / M tokens | $10 | $120 |
| Results tracked | 6 | 12 |
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Category by category
Coding GPT-5 Pro leads
GPT-5.1-Codex: 41.9 (#116), GPT-5 Pro: 44.0 (#80)
| Benchmark | GPT-5.1-Codex | GPT-5 Pro |
|---|---|---|
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| WeirdML | — | 60.4% |
| ALE-Bench | 1,245 | — |
| AlgoTune | — | 1.31 |
Agentic & Tool Use Not comparable
GPT-5.1-Codex: 38.0 (#33), GPT-5 Pro: —
| Benchmark | GPT-5.1-Codex | GPT-5 Pro |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, GPT-5 Pro: 38.9 (#62)
| Benchmark | GPT-5.1-Codex | GPT-5 Pro |
|---|---|---|
| ARC-AGI-2 | — | 18.3% |
| SimpleBench | — | 61.6% |
| Kagi LLM Benchmark | — | 76.8% |
| ARC-AGI-1 | — | 70.2% |
| EnigmaEval | — | 18.8% |
| Epoch Capabilities Index | — | 150.28 |
Math GPT-5 Pro leads
GPT-5.1-Codex: 30.3 (#235), GPT-5 Pro: 48.5 (#63)
| Benchmark | GPT-5.1-Codex | GPT-5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 55.8% |
| FrontierMath Tier 4 | — | 19.5% |
| ProofBench | 9% | — |
| FrontierMath Tier 4 (v1) | — | 14.6% |
Knowledge Not comparable
GPT-5.1-Codex: —, GPT-5 Pro: 56.7 (#42)
| Benchmark | GPT-5.1-Codex | GPT-5 Pro |
|---|---|---|
| Humanity's Last Exam | — | 31.6% |
Frequently asked questions
Is GPT-5.1-Codex better than GPT-5 Pro?
GPT-5 Pro is the stronger model overall, scoring 46.4 to 38.6 on the Noometry Index. GPT-5.1-Codex costs 12× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5.1-Codex or GPT-5 Pro?
GPT-5.1-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; GPT-5 Pro lists at $15 and $120.
Is GPT-5.1-Codex or GPT-5 Pro better for coding?
GPT-5 Pro scores higher on coding benchmarks: 44.0 versus 41.9 in the Noometry coding category.
Which has the bigger context window?
Both accept 400K tokens.
How many benchmarks do GPT-5.1-Codex and GPT-5 Pro share?
0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and GPT-5 Pro has 12.