GPT-5.6 Sol
GPT-5.6 Sol is an API-only (closed weights) language model from OpenAI, released July 9, 2026. The context window is 1.1M tokens. On the Epoch Capabilities Index it scores 163.0, rank 13 of 256 rated models. API price: $4 input / $20 output per million tokens.
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Lab
OpenAI
Released
July 9, 2026
Weights
API-only (closed weights)
Parameters
–
Context
1.1M
Price / M tokens
$4 / $20 in / out
Epoch ECI
163.0 #13
Strengths by category
ModelTape's 0–100 fit on Epoch AI benchmark results.
| Category | Score | Based on |
|---|---|---|
| Reasoning | 39.6 | Chess Puzzles, SimpleBench, Mystery Game Puzzles |
| Math | 76.0 | ProofBench, OTIS Mock AIME 2024-2025, FrontierMath-Tiers-1-3-v2-Private, FrontierMath-Tier-4-v2-Private |
| Coding | 65.5 | GSO-Bench, MirrorCode, FrontierSWE, DeepSWE |
| Agent | 35.6 | Balrog, OSWorld 2.0 |
| Knowledge | 82.5 | GPQA diamond, SimpleQA Verified |
Benchmark results
| Benchmark (Epoch AI) | Score |
|---|---|
| OTIS Mock AIME | 100.0% |
| GPQA Diamond | 95.1% |
| FrontierMath (Tiers 1–3) | 93.8% |
| ProofBench | 83.0% |
| FrontierMath-Tier-4-v2-Private | 82.9% |
| GSO-Bench | 76.5% |
| DeepSWE | 72.7% |
| SimpleQA Verified | 69.7% |
| Chess Puzzles | 66.3% |
| SimpleBench | 66.0% |
| Balrog | 60.0% |
| Mystery Game Puzzles | 53.7% |
| EBR-bench | 44.8% |
| Furniture Assembly | 38.1% |
| FrontierSWE | 32.2% |
| OSWorld 2.0 | 27.3% |
| MirrorCode | 20.0% |
Links
Announcement · Epoch AI benchmarks
Models with a similar score
Claude Fable 5.1 · Claude Sonnet 5.5 · Gemini 4 Argon · Claude Opus 5 · Claude Fable 5 · GPT-6 Sol · GPT-5.5 Pro · Muse Wonder
More from OpenAI
GPT-6.1 Terra · GPT-6.1 Sol · GPT-6 Sol · GPT-6 Luna · GPT-6 Astra · GPT-5.6 Cyber · Daybreak Red · Daybreak Blue