Claude Mythos Preview vs Gemini 3.1 Flash-Lite
Claude Mythos Preview (2026) and Gemini 3.1 Flash-Lite (2026) are frontier reasoning models from Anthropic and Google DeepMind. Claude Mythos Preview ships a 1m-token context window, while Gemini 3.1 Flash-Lite ships a 1.05m-token context window. On Google-Proof Q&A, Claude Mythos Preview leads by 7.7 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3.1 Flash-Lite is ~9900% cheaper at $0.25/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos Preview | Gemini 3.1 Flash-Lite |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps, tool-calling agents, and long-context analysis |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1.05m |
| Cheapest output | $125/1M tokens | $1.50/1M tokens |
| Provider routes | 2 tracked | 3 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 1 shared |
Decision tradeoffs
- Claude Mythos Preview holds a shared-benchmark lead on Google-Proof Q&A, ahead by 7.7 points.
- Claude Mythos Preview uniquely exposes Reasoning in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- Gemini 3.1 Flash-Lite has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.1 Flash-Lite has the lower cheapest tracked output price at $1.50/1M tokens.
- Gemini 3.1 Flash-Lite has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Gemini 3.1 Flash-Lite for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Mythos Preview
$51,250
Cheapest tracked route/tier: Anthropic
Gemini 3.1 Flash-Lite
$575
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $50,675. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos Preview and Gemini 3.1 Flash-Lite; plan for SDK, billing, or endpoint changes.
- Gemini 3.1 Flash-Lite is $124/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- No overlapping tracked provider route is sourced for Gemini 3.1 Flash-Lite and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
- Claude Mythos Preview is $124/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-01 | 2026-05-07 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-12 | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input price | $25/1M tokens | $0.25/1M tokens |
| Output price | $125/1M tokens | $1.50/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | Gemini 3.1 Flash-Lite |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Mythos Preview | Gemini 3.1 Flash-Lite |
|---|---|---|
| Google-Proof Q&A | 94.6 | 86.9 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Claude Mythos Preview at 94.6 and Gemini 3.1 Flash-Lite at 86.9, with Claude Mythos Preview ahead by 7.7 points. The largest visible gap is 7.7 points on Google-Proof Q&A, 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. 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.
For cost, Claude Mythos Preview lists $25/1M input and $125/1M output tokens on the cheapest tracked provider, while Gemini 3.1 Flash-Lite lists $0.25/1M input and $1.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Flash-Lite lower by about $54.38 per million blended tokens. Availability is 2 providers versus 3, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support are central to the workload. Choose Gemini 3.1 Flash-Lite when coding workflow support, larger context windows, and lower input-token cost 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 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite supports 1.05m tokens, while Claude Mythos Preview supports 1m tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Mythos Preview or Gemini 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. Gemini 3.1 Flash-Lite costs $0.25/1M input and $1.50/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or Gemini 3.1 Flash-Lite open source?
Claude Mythos Preview is listed under Proprietary. Gemini 3.1 Flash-Lite 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 3.1 Flash-Lite?
Both Claude Mythos Preview and Gemini 3.1 Flash-Lite 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 3.1 Flash-Lite?
Both Claude Mythos Preview and Gemini 3.1 Flash-Lite expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Mythos Preview and Gemini 3.1 Flash-Lite?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. Gemini 3.1 Flash-Lite is available on Google AI Studio, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.