Claude Opus 4.5 vs Gemini 3 Flash Preview
Claude Opus 4.5 (2025) and Gemini 3 Flash Preview (2025) are frontier reasoning models from Anthropic and Google DeepMind. Claude Opus 4.5 ships a 200k-token context window, while Gemini 3 Flash Preview ships a 1m-token context window. On pricing, Gemini 3 Flash Preview costs $0.50/1M input tokens versus $5/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3 Flash Preview is ~900% cheaper at $0.50/1M; pay for Claude Opus 4.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.5 | Gemini 3 Flash Preview |
|---|---|---|
| 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 | 200k | 1m |
| Cheapest output | $25/1M tokens | $3/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Claude Opus 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Opus 4.5 uniquely exposes Reasoning in local model data.
- Local decision data tags Claude Opus 4.5 for Coding, RAG, and Agents.
- Gemini 3 Flash Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3 Flash Preview has the lower cheapest tracked output price at $3/1M tokens.
- Local decision data tags Gemini 3 Flash Preview 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 Opus 4.5
$10,250
Cheapest tracked route/tier: Microsoft Foundry
Gemini 3 Flash Preview
$1,150
Cheapest tracked route/tier: GCP Vertex AI
Estimated monthly gap: $9,100. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on GCP Vertex AI and OpenRouter; start route-level A/B tests there.
- Gemini 3 Flash Preview is $22/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Provider overlap exists on GCP Vertex AI and OpenRouter; start route-level A/B tests there.
- Claude Opus 4.5 is $22/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Opus 4.5 adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-01 | 2025-12-17 |
| Context window | 200k | 1m |
| 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 Opus 4.5 | Gemini 3 Flash Preview |
|---|---|---|
| Input price | $5/1M tokens | $0.50/1M tokens |
| Output price | $25/1M tokens | $3/1M tokens |
| Providers |
Capabilities
| Capability | Claude Opus 4.5 | Gemini 3 Flash Preview |
|---|---|---|
| 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
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Claude Opus 4.5. 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 Opus 4.5 lists $5/1M input and $25/1M output tokens on the cheapest tracked provider, while Gemini 3 Flash Preview lists $0.50/1M input and $3/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3 Flash Preview lower by about $9.75 per million blended tokens. Availability is 6 providers versus 3, so concentration risk also matters.
Choose Claude Opus 4.5 when coding workflow support and broader provider choice are central to the workload. Choose Gemini 3 Flash Preview 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. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Claude Opus 4.5 or Gemini 3 Flash Preview?
Gemini 3 Flash Preview supports 1m tokens, while Claude Opus 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 Opus 4.5 or Gemini 3 Flash Preview?
Gemini 3 Flash Preview is cheaper on tracked token pricing. Claude Opus 4.5 costs $5/1M input and $25/1M output tokens. Gemini 3 Flash Preview costs $0.50/1M input and $3/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Opus 4.5 or Gemini 3 Flash Preview open source?
Claude Opus 4.5 is listed under Proprietary. Gemini 3 Flash 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 Opus 4.5 or Gemini 3 Flash Preview?
Both Claude Opus 4.5 and Gemini 3 Flash 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 Opus 4.5 or Gemini 3 Flash Preview?
Both Claude Opus 4.5 and Gemini 3 Flash 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 Opus 4.5 and Gemini 3 Flash Preview?
Claude Opus 4.5 is available on Microsoft Foundry, Anthropic, GCP Vertex AI, AWS Bedrock, and OpenRouter. Gemini 3 Flash Preview is available on GCP Vertex AI, OpenRouter, and Google AI Studio. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-15. Data sourced from public model cards and provider documentation.