Claude Mythos Preview vs o3
Claude Mythos Preview (2026) and o3 (2025) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Mythos Preview ships a 1M-token context window, while o3 ships a 200K-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 22.2 pts. On pricing, o3 costs $2/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
o3 is ~1150% cheaper at $2/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos Preview | o3 |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 200K |
| Cheapest output | $125/1M tokens | $8/1M tokens |
| Provider routes | 2 tracked | 2 tracked |
| Shared benchmarks | SWE-bench Verified leader | 2 rows |
Decision tradeoffs
- Claude Mythos Preview leads the largest shared benchmark signal on SWE-bench Verified by 22.2 points.
- Claude Mythos Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos Preview uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- o3 has the lower cheapest tracked output price at $8/1M tokens.
- Local decision data tags o3 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
o3
$3,600
Cheapest tracked route: OpenAI API
Estimated monthly gap: $47,650. 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 o3; plan for SDK, billing, or endpoint changes.
- o3 is $117/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Function calling before moving production traffic.
- No overlapping tracked provider route is sourced for o3 and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
- Claude Mythos Preview is $117/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Vision, Multimodal, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2025-03-31 |
| Context window | 1M | 200K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | o3 |
|---|---|---|
| Input price | $25/1M tokens | $2/1M tokens |
| Output price | $125/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | o3 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Claude Mythos Preview | o3 |
|---|---|---|
| SWE-bench Verified | 93.9 | 71.7 |
| Google-Proof Q&A | 94.6 | 87.7 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Mythos Preview at 93.9 and o3 at 71.7, with Claude Mythos Preview ahead by 22.2 points; Google-Proof Q&A has Claude Mythos Preview at 94.6 and o3 at 87.7, with Claude Mythos Preview ahead by 6.9 points. The largest visible gap is 22.2 points on SWE-bench Verified, 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 vision: Claude Mythos Preview, multimodal input: Claude Mythos Preview, function calling: Claude Mythos Preview, and tool use: Claude Mythos Preview. Both models share reasoning mode, structured outputs, and code execution, 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, while o3 lists $2/1M input and $8/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts o3 lower by about $51.20 per million blended tokens. Availability is 2 providers versus 2, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support and larger context windows are central to the workload. Choose o3 when coding workflow support 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 o3?
Claude Mythos Preview supports 1M tokens, while o3 supports 200K 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 o3?
o3 is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. o3 costs $2/1M input and $8/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or o3 open source?
Claude Mythos Preview is listed under Proprietary. o3 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 o3?
Claude Mythos Preview has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Mythos Preview or o3?
Claude Mythos Preview has the clearer documented multimodal input signal in this comparison. If multimodal input 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 o3?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. o3 is available on OpenAI API and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.