Claude Haiku 4.5 vs Claude Mythos Preview
Claude Haiku 4.5 (2025) and Claude Mythos Preview (2026) are frontier reasoning models from Anthropic. Claude Haiku 4.5 ships a 200k-token context window, while Claude Mythos Preview ships a 1M-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 20.6 pts. On pricing, Claude Haiku 4.5 costs $0.8/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Claude Haiku 4.5 is ~3025% cheaper at $0.8/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Haiku 4.5 | Claude Mythos Preview |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 200k | 1M |
| Cheapest output | $4/1M tokens | $125/1M tokens |
| Provider routes | 7 tracked | 2 tracked |
| Shared benchmarks | 1 rows | SWE-bench Verified leader |
Decision tradeoffs
- Claude Haiku 4.5 has the lower cheapest tracked output price at $4/1M tokens.
- Claude Haiku 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Claude Haiku 4.5 for Coding, RAG, and Agents.
- Claude Mythos Preview leads the largest shared benchmark signal on SWE-bench Verified by 20.6 points.
- Claude Mythos Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos Preview uniquely exposes Reasoning in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Haiku 4.5
$1,640
Cheapest tracked route: AWS Bedrock
Claude Mythos Preview
$51,250
Cheapest tracked route: Anthropic
Estimated monthly gap: $49,610. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Anthropic and Microsoft Foundry; start route-level A/B tests there.
- Claude Mythos Preview is $121/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Reasoning in local capability data.
- Provider overlap exists on Microsoft Foundry and Anthropic; start route-level A/B tests there.
- Claude Haiku 4.5 is $121/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-10-01 | 2026-04-07 |
| Context window | 200k | 1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-02 | 2025-12 |
Pricing and availability
| Pricing attribute | Claude Haiku 4.5 | Claude Mythos Preview |
|---|---|---|
| Input price | $0.8/1M tokens | $25/1M tokens |
| Output price | $4/1M tokens | $125/1M tokens |
| Providers |
Capabilities
| Capability | Claude Haiku 4.5 | Claude Mythos Preview |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Claude Haiku 4.5 | Claude Mythos Preview |
|---|---|---|
| SWE-bench Verified | 73.3 | 93.9 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Haiku 4.5 at 73.3 and Claude Mythos Preview at 93.9, with Claude Mythos Preview ahead by 20.6 points. The largest visible gap is 20.6 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 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 Haiku 4.5 lists $0.8/1M input and $4/1M output tokens, while Claude Mythos Preview lists $25/1M input and $125/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Claude Haiku 4.5 lower by about $53.24 per million blended tokens. Availability is 7 providers versus 2, so concentration risk also matters.
Choose Claude Haiku 4.5 when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose Claude Mythos Preview when coding workflow support and larger context windows 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 Haiku 4.5 or Claude Mythos Preview?
Claude Mythos Preview supports 1M tokens, while Claude Haiku 4.5 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 Haiku 4.5 or Claude Mythos Preview?
Claude Haiku 4.5 is cheaper on tracked token pricing. Claude Haiku 4.5 costs $0.8/1M input and $4/1M output tokens. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Haiku 4.5 or Claude Mythos Preview open source?
Claude Haiku 4.5 is listed under Proprietary. Claude Mythos Preview 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 Haiku 4.5 or Claude Mythos Preview?
Both Claude Haiku 4.5 and Claude Mythos Preview 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 Haiku 4.5 or Claude Mythos Preview?
Both Claude Haiku 4.5 and Claude Mythos Preview 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 Haiku 4.5 and Claude Mythos Preview?
Claude Haiku 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, AWS Bedrock, and GCP Vertex AI. Claude Mythos Preview is available on Anthropic and Microsoft Foundry. 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.