Claude Mythos Preview vs Gemini 3 Flash
Claude Mythos Preview (2026) and Gemini 3 Flash (2025) are frontier reasoning models from Anthropic and Google DeepMind. Claude Mythos Preview ships a 1M-token context window, while Gemini 3 Flash ships a 1M-token context window. On τ-bench, Claude Mythos Preview leads by 17.7 pts. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Claude Mythos Preview is safer overall; choose Gemini 3 Flash when coding workflow support matters.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2025-12-17 |
| Context window | 1M | 1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | Gemini 3 Flash |
|---|---|---|
| Input price | - | $0.1/1M tokens |
| Output price | - | $0.4/1M tokens |
| Providers | - |
Capabilities
| Capability | Claude Mythos Preview | Gemini 3 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Claude Mythos Preview | Gemini 3 Flash |
|---|---|---|
| τ-bench | 89.2 | 71.5 |
Deep dive
On shared benchmark coverage, τ-bench has Claude Mythos Preview at 89.2 and Gemini 3 Flash at 71.5, with Claude Mythos Preview ahead by 17.7 points. The largest visible gap is 17.7 points on τ-bench, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on reasoning mode: Claude Mythos Preview and structured outputs: Claude Mythos Preview. Both models share vision, multimodal input, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: Claude Mythos Preview has no token price sourced yet and Gemini 3 Flash has $0.1/1M input tokens. Provider availability is 0 tracked routes versus 2. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Claude Mythos Preview when coding workflow support are central to the workload. Choose Gemini 3 Flash when coding workflow support and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Mythos Preview or Gemini 3 Flash?
Claude Mythos Preview supports 1M tokens, while Gemini 3 Flash supports 1M tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Claude Mythos Preview or Gemini 3 Flash open source?
Claude Mythos Preview is listed under Proprietary. Gemini 3 Flash is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Mythos Preview or Gemini 3 Flash?
Both Claude Mythos Preview and Gemini 3 Flash expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Claude Mythos Preview or Gemini 3 Flash?
Both Claude Mythos Preview and Gemini 3 Flash expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Claude Mythos Preview or Gemini 3 Flash?
Claude Mythos Preview has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Mythos Preview and Gemini 3 Flash?
Claude Mythos Preview is available on the tracked providers still being sourced. Gemini 3 Flash is available on Replicate API and GCP Vertex AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.