Model comparison
GPT-5.1-Codex vs GPT-6 Sol
GPT-6 Sol is the stronger model overall, scoring 49.2 to 38.2 on the Noometry Index.
Last verified . 1 shared benchmarks.
Summary
- They share 1 benchmark with published results for both. GPT-5.1-Codex scores higher in 1 category and GPT-6 Sol in 2 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in coding, where GPT-6 Sol leads 59.6 to 41.7.
- GPT-5.1-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $2 / $10 for GPT-6 Sol.
- GPT-6 Sol accepts more context: 1.05M tokens versus 400K.
Side by side
| GPT-5.1-Codex | GPT-6 Sol | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 38.2 | 49.2 |
| Released | 2025-11-12 | 2026-09-22 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 1.05M |
| Max output | 128K | 128K |
| Input $ / M tokens | $1.25 | $2 |
| Output $ / M tokens | $10 | $10 |
| Results tracked | 6 | 22 |
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Category by category
Coding GPT-6 Sol leads
GPT-5.1-Codex: 41.7 (#107), GPT-6 Sol: 59.6 (#11)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| LMArena WebDev | 1337 | 1692 |
| DeepSWE | — | 68.8% |
| FrontierCode | — | 49.3% |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena Coding | — | 1453 |
| ALE-Bench | 1,245 | — |
Agentic & Tool Use GPT-5.1-Codex leads
GPT-5.1-Codex: 37.8 (#32), GPT-6 Sol: 33.5 (#49)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| GDP.pdf | — | 28% |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 49.3 (#34)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| NYT Connections (extended) | — | 90.1% |
| EBR-Bench | — | 53.3% |
| LMArena Hard Prompts | — | 1420 |
Math GPT-6 Sol leads
GPT-5.1-Codex: 29.3 (#218), GPT-6 Sol: 35.8 (#135)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| ProofBench | 9% | — |
| LMArena Math | — | 1404 |
Knowledge Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 43.0 (#87)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| Vectara Hallucination Rate | — | 6.5% |
| LMArena Expert | — | 1449 |
Multimodal Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 47.6 (#9)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| Furniture Assembly | — | 58.3% |
Multilingual Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 51.0 (#113)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| LMArena Non-English | — | 1389 |
| LMArena Chinese | — | 1416 |
| LMArena Russian | — | 1407 |
| LMArena Spanish | — | 1377 |
Instruction Following Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 74.4 (#97)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| LMArena Instruction Following | — | 1406 |
Long Context Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 43.2 (#100)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| LMArena Longer Query | — | 1415 |
Writing & Preference Not comparable
GPT-5.1-Codex: —, GPT-6 Sol: 72.3 (#15)
| Benchmark | GPT-5.1-Codex | GPT-6 Sol |
|---|---|---|
| LMArena Text | — | 1396 |
| LMArena Creative Writing | — | 1392 |
| EQ-Bench Creative Writing | — | 2125 |
| LMArena Multi-Turn | — | 1405 |
Frequently asked questions
Is GPT-5.1-Codex better than GPT-6 Sol?
GPT-6 Sol is the stronger model overall, scoring 49.2 to 38.2 on the Noometry Index.
Which is cheaper, GPT-5.1-Codex or GPT-6 Sol?
GPT-5.1-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; GPT-6 Sol lists at $2 and $10.
Is GPT-5.1-Codex or GPT-6 Sol better for coding?
GPT-6 Sol scores higher on coding benchmarks: 59.6 versus 41.7 in the Noometry coding category.
Which has the bigger context window?
GPT-6 Sol does, with 1.05M tokens against 400K.
How many benchmarks do GPT-5.1-Codex and GPT-6 Sol share?
1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and GPT-6 Sol has 22.