Claude Mythos Preview vs GPT-5 Mini
Claude Mythos Preview (2026) and GPT-5 Mini (2025) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Mythos Preview ships a 1M-token context window, while GPT-5 Mini ships a 400K-token context window. On pricing, GPT-5 Mini costs $0.25/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
GPT-5 Mini 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 | GPT-5 Mini |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 400K |
| Cheapest output | $125/1M tokens | $2/1M tokens |
| Provider routes | 2 tracked | 3 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Claude Mythos Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- GPT-5 Mini has the lower cheapest tracked output price at $2/1M tokens.
- GPT-5 Mini has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags GPT-5 Mini for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Mythos Preview
$51,250
Cheapest tracked route: Anthropic
GPT-5 Mini
$700
Cheapest tracked route: Replicate API
Estimated monthly gap: $50,550. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos Preview and GPT-5 Mini; plan for SDK, billing, or endpoint changes.
- GPT-5 Mini is $123/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- No overlapping tracked provider route is sourced for GPT-5 Mini and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
- Claude Mythos Preview is $123/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2025-08-07 |
| Context window | 1M | 400K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | 2024-05 |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | GPT-5 Mini |
|---|---|---|
| Input price | $25/1M tokens | $0.25/1M tokens |
| Output price | $125/1M tokens | $2/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | GPT-5 Mini |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint is close: both models cover vision, multimodal input, reasoning mode, function calling, and tool use. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, Claude Mythos Preview lists $25/1M input and $125/1M output tokens, while GPT-5 Mini lists $0.25/1M input and $2/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GPT-5 Mini lower by about $54.23 per million blended tokens. Availability is 2 providers versus 3, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support and larger context windows are central to the workload. Choose GPT-5 Mini when coding workflow support, lower input-token cost, 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. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Claude Mythos Preview or GPT-5 Mini?
Claude Mythos Preview supports 1M tokens, while GPT-5 Mini supports 400K 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 GPT-5 Mini?
GPT-5 Mini is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. GPT-5 Mini costs $0.25/1M input and $2/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or GPT-5 Mini open source?
Claude Mythos Preview is listed under Proprietary. GPT-5 Mini 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 GPT-5 Mini?
Both Claude Mythos Preview and GPT-5 Mini expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Mythos Preview or GPT-5 Mini?
Both Claude Mythos Preview and GPT-5 Mini 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 GPT-5 Mini?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. GPT-5 Mini is available on Replicate API, OpenRouter, and OpenAI API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.