Claude Opus 4.8 vs Gemini 3.5 Flash
Claude Opus 4.8 (2026) and Gemini 3.5 Flash (2026) are frontier-tier reasoning models from Anthropic and Google DeepMind. Claude Opus 4.8 ships a 1m-token context window, while Gemini 3.5 Flash ships a 1.05m-token context window. On SWE-bench Verified, Claude Opus 4.8 leads by 10.6 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3.5 Flash is ~233% cheaper at $1.50/1M; pay for Claude Opus 4.8 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.8 | Gemini 3.5 Flash |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1.05m |
| Cheapest output | $25/1M tokens | $9/1M tokens |
| Provider routes | 6 tracked | 4 tracked |
| Shared benchmarks | SWE-bench Verified leader | 4 shared |
Decision tradeoffs
- Claude Opus 4.8 holds a shared-benchmark lead on SWE-bench Verified, ahead by 10.6 points.
- Claude Opus 4.8 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Opus 4.8 uniquely exposes Computer use and Parallel agents in local model data.
- Local decision data tags Claude Opus 4.8 for Coding, RAG, and Agents.
- Gemini 3.5 Flash holds a shared-benchmark lead on MCP-Atlas, ahead by 1.4 points.
- Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.5 Flash has the lower cheapest tracked output price at $9/1M tokens.
- Local decision data tags Gemini 3.5 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 4.8
$10,250
Cheapest tracked route/tier: Anthropic
Gemini 3.5 Flash
$3,450
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $6,800. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on GCP Vertex AI, Vercel AI Gateway, and OpenRouter; start route-level A/B tests there.
- Gemini 3.5 Flash is $16/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Computer use and Parallel agents 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 4.8 is $16/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Opus 4.8 adds Computer use and Parallel agents in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-28 | 2026-05-19 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2026-01 | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Opus 4.8 | Gemini 3.5 Flash |
|---|---|---|
| Input price | $5/1M tokens | $1.50/1M tokens |
| Output price | $25/1M tokens | $9/1M tokens |
| Providers |
Capabilities
| Capability | Claude Opus 4.8 | Gemini 3.5 Flash |
|---|---|---|
| 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 |
| IDE integration | No | No |
| Computer use | Yes | No |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Opus 4.8 | Gemini 3.5 Flash |
|---|---|---|
| SWE-bench Verified | 88.6 | 78.0 |
| SWE-bench Pro | 69.2 | 55.1 |
| Google-Proof Q&A | 93.6 | 92.2 |
| MCP-Atlas | 82.2 | 83.6 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Opus 4.8 at 88.6 and Gemini 3.5 Flash at 78, with Claude Opus 4.8 ahead by 10.6 points; SWE-bench Pro has Claude Opus 4.8 at 69.2 and Gemini 3.5 Flash at 55.1, with Claude Opus 4.8 ahead by 14.1 points; Google-Proof Q&A has Claude Opus 4.8 at 93.6 and Gemini 3.5 Flash at 92.2, with Claude Opus 4.8 ahead by 1.4 points. The largest visible gap is 14.1 points on SWE-bench Pro, 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 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 Opus 4.8 lists $5/1M input and $25/1M output tokens on the cheapest tracked provider, while Gemini 3.5 Flash lists $1.50/1M input and $9/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.5 Flash lower by about $7.25 per million blended tokens. Availability is 6 providers versus 4, so concentration risk also matters.
Choose Claude Opus 4.8 when coding workflow support and broader provider choice are central to the workload. Choose Gemini 3.5 Flash 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.
FAQ
Which has a larger context window, Claude Opus 4.8 or Gemini 3.5 Flash?
Gemini 3.5 Flash supports 1.05m tokens, while Claude Opus 4.8 supports 1m 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 4.8 or Gemini 3.5 Flash?
Gemini 3.5 Flash is cheaper on tracked token pricing. Claude Opus 4.8 costs $5/1M input and $25/1M output tokens. Gemini 3.5 Flash costs $1.50/1M input and $9/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Opus 4.8 or Gemini 3.5 Flash open source?
Claude Opus 4.8 is listed under Proprietary. Gemini 3.5 Flash 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 4.8 or Gemini 3.5 Flash?
Both Claude Opus 4.8 and Gemini 3.5 Flash 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 4.8 or Gemini 3.5 Flash?
Both Claude Opus 4.8 and Gemini 3.5 Flash 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 4.8 and Gemini 3.5 Flash?
Claude Opus 4.8 is available on Anthropic, AWS Bedrock, GCP Vertex AI, Microsoft Foundry, and OpenRouter. Gemini 3.5 Flash is available on Google AI Studio, GCP Vertex AI, Vercel AI Gateway, and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-17. Data sourced from public model cards and provider documentation.