Model comparison
Claude Mythos Preview vs GPT-5.5 Pro
GPT-5.5 Pro has enough public results to be ranked (#8); Claude Mythos Preview does not yet, so treat this comparison as directional.
Last verified . 0 shared benchmarks.
Side by side
| Claude Mythos Preview | GPT-5.5 Pro | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 41.2 | 64.3 |
| Released | 2026-04-07 | 2026-04-23 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1.05M |
| Max output | — | 128K |
| Input $ / M tokens | — | $30 |
| Output $ / M tokens | — | $180 |
| Results tracked | 2 | 14 |
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Category by category
Agentic & Tool Use Not comparable
Claude Mythos Preview: 41.4, GPT-5.5 Pro: —
| Benchmark | Claude Mythos Preview | GPT-5.5 Pro |
|---|---|---|
| ExploitBench | 73.8% | — |
| METR Time Horizons | 85.2% | — |
Reasoning Not comparable
Claude Mythos Preview: —, GPT-5.5 Pro: 73.3 (#10)
| Benchmark | Claude Mythos Preview | GPT-5.5 Pro |
|---|---|---|
| ARC-AGI-2 | — | 84.6% |
| SimpleBench | — | 76.9% |
| ARC-AGI-1 | — | 96.5% |
| CritPt | — | 30.6% |
| Chess Puzzles | — | 64% |
| DTBench | — | 96% |
| LMCA | — | 53.9% |
| Epoch Capabilities Index | — | 162.07 |
Math Not comparable
Claude Mythos Preview: —, GPT-5.5 Pro: 84.0 (#10)
| Benchmark | Claude Mythos Preview | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 87.7% |
| FrontierMath Tier 4 | — | 78% |
| OTIS Mock AIME 2024-2025 | — | 100% |
| FrontierMath (Feb 2025 set) | — | 52.4% |
| FrontierMath Tier 4 (v1) | — | 39.6% |
Knowledge Not comparable
Claude Mythos Preview: —, GPT-5.5 Pro: 64.1 (#19)
| Benchmark | Claude Mythos Preview | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | — | 93.9% |
Frequently asked questions
Is Claude Mythos Preview better than GPT-5.5 Pro?
GPT-5.5 Pro has enough public results to be ranked (#8); Claude Mythos Preview does not yet, so treat this comparison as directional.
How many benchmarks do Claude Mythos Preview and GPT-5.5 Pro share?
0 benchmarks have published results for both models. Claude Mythos Preview has 2 scored results on Noometry and GPT-5.5 Pro has 14.