What Do the 2026 Benchmark Tables Actually Show?
OpenAI's GPT-5.6 launch data, published July 9, 2026, compares its Sol, Terra, and Luna tiers against Claude Fable 5, Claude Mythos 5, Claude Opus 4.8, and Gemini 3.1 Pro Preview across roughly a dozen categories. The headline pattern: GPT-5.6 wins on efficiency-weighted and agentic evaluations, Claude wins on several depth-heavy reasoning and software engineering tests, and Gemini 3.1 Pro Preview trails both on most listed evals.
Where Does GPT-5.6 Lead in 2026?
| Eval (per OpenAI) | GPT-5.6 Sol | Best Claude Listed | Gemini 3.1 Pro |
|---|---|---|---|
| Agents' Last Exam | 52.7% | 45.2% (Opus 4.8) | 32.1% |
| OSWorld 2.0 | 62.6% | 54.8% (Opus 4.8) | Not listed |
| BrowseComp | 90.4% (92.2% ultra) | 88% (Mythos 5) | 85.9% |
| BenchCAD | 70.6% | 38.4% (Mythos 5) | Not listed |
| Coding Agent Index v1.1 | 80 | 77.2 (Fable 5) | 42.7 |
| GPQA Diamond | 94.6% | 94.6% (Mythos Preview) | 94.3% |
The pattern in GPT-5.6's wins is long-horizon agentic work: browsing, operating computers, CAD manipulation, and multi-step professional workflows. OpenAI also stresses that many of these results come with fewer output tokens and lower estimated cost, which is the real competitive claim of 2026.
Where Does Claude Still Lead in 2026?
| Eval (per OpenAI) | Best Claude Listed | GPT-5.6 Sol |
|---|---|---|
| SWE-Bench Pro | 80.3% (Mythos 5) | 64.6% |
| GDPval-AA v2 | 1,759.6 Elo (Fable 5) | 1,747.8 Elo |
| Artificial Analysis Intelligence Index v4.1 | 59.9 (Fable 5) | 58.9 |
| FrontierMath Tier 4 (v2) | 87.8% (Fable 5) | 83% |
| Toolathlon | 61.7% (Mythos 5 / Fable 5) | 58% |
| GraphWalks BFS 1M f1 | 79.4% (Mythos 5) | 77.1% |
Claude's strongholds in 2026 are real-codebase software engineering, professional task quality Elo, frontier mathematics, long-context graph reasoning, and marathon tool use. Notably, several of these Claude leads appear inside OpenAI's own launch tables, which adds credibility to both sides of the picture. OpenAI's counter-argument is cost: it claims comparable intelligence at roughly half the estimated cost and 61 percent less time on the Intelligence Index.
How Should You Read Vendor Benchmarks in 2026?
- Source bias 2026: All figures here come from OpenAI's launch post. Vendors choose which evals, settings, and competitor configurations to publish. Anthropic's and Google's own posts will frame different tables.
- Missing cells matter 2026: Many Claude and Gemini cells are simply not reported. Absence of a number is not evidence of weakness.
- Footnote fine print 2026: OpenAI notes some scoring methods are not comparable to results in other vendors' system cards, and some latency figures were rescaled from a faster alpha API.
- Efficiency vs peak 2026: GPT-5.6's core claim is performance per dollar; Claude's is peak depth on hard reasoning and engineering. Both can be true simultaneously.
Which Model Should Your Business Choose in 2026?
The honest 2026 answer is portfolio, not monogamy. High-volume agentic automation, browsing research, and cost-sensitive pipelines favor the GPT-5.6 family's economics, especially Terra and Luna. Deep software engineering on real codebases, complex professional analysis, and frontier math currently favor Claude's top tiers on the published numbers. Gemini remains worth watching, particularly where Google ecosystem integration matters, though it trails on most evals in this particular table. The winning move is routing: assign each workflow to the model that measurably performs best on your own evaluation set, and re-test quarterly because 2026 release cycles are now measured in weeks.