Claude Opus 4.5 vs Gemini 2.5 Flash
Claude Opus 4.5 (2025) and Gemini 2.5 Flash (2025) are frontier reasoning models from Anthropic and Google DeepMind. Claude Opus 4.5 ships a 200k-token context window, while Gemini 2.5 Flash ships a 1m-token context window. On MMLU PRO, Claude Opus 4.5 leads by 0.5 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 2.5 Flash is ~1567% cheaper at $0.30/1M; pay for Claude Opus 4.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.5 | Gemini 2.5 Flash |
|---|---|---|
| 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 | $2.50/1M tokens |
| Provider routes | 6 tracked | 6 tracked |
| Shared benchmarks | MMLU PRO leader | 6 shared |
Decision tradeoffs
- Claude Opus 4.5 holds a shared-benchmark lead on MMLU PRO, ahead by 0.5 points.
- 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 2.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 2.5 Flash has the lower cheapest tracked output price at $2.50/1M tokens.
- Local decision data tags Gemini 2.5 Flash 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 2.5 Flash
$865
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $9,385. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on GCP Vertex AI, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
- Gemini 2.5 Flash is $22.50/1M 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, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
- Claude Opus 4.5 is $22.50/1M 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 | 2025-06-17 |
| Context window | 200k | 1m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-12 | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Opus 4.5 | Gemini 2.5 Flash |
|---|---|---|
| Input price | $5/1M tokens | $0.30/1M tokens |
| Output price | $25/1M tokens | $2.50/1M tokens |
| Providers |
Capabilities
| Capability | Claude Opus 4.5 | Gemini 2.5 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| JSON / 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 Opus 4.5 | Gemini 2.5 Flash |
|---|---|---|
| MMLU PRO | 88.9 | 88.4 |
| Google-Proof Q&A | 87.0 | 82.8 |
| Massive Multi-discipline Multimodal Understanding | 80.7 | 79.7 |
| Chatbot Arena | 1466.0 | 1320.0 |
| BFCL | 77.5 | 56.2 |
| Aider Polyglot | 72.0 | 55.1 |
Continue comparing
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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.