Claude Opus 4.8 vs Gemini 3.1 Pro: premium reasoning or massive context?
Gemini 3.1 Pro for workloads that need huge context windows, multimodal processing, or the lowest price per token in the premium tier. Claude Opus 4.8 for tasks where reasoning depth is the primary requirement and you're willing to pay a premium for Anthropic's best model.
Anthropic's refined flagship versus Google's context-window king.
Claude Opus 4.8 is Anthropic's latest flagship reasoning model with refined instruction following. Gemini 3.1 Pro is Google's premium model with a 1M token context window. Opus 4.8 costs more at the short-context tier, but the choice isn't just about price. It depends on whether you need Gemini's larger context and multimodal inputs or Opus's reasoning profile.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.
Side-by-side specs
| Spec | Claude Opus 4.8 | Gemini 3.1 Pro |
|---|---|---|
| Input Cost (per M) | $5.00 | $2.00 (better on this spec) |
| Output Cost (per M) | $25.00 | $12.00 (better on this spec) |
| Cached Input (per M) | $0.50 | $0.20 (better on this spec) |
| Context Window | 500K | 1M (better on this spec) |
How they differ
Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens, with a 90% caching discount. Gemini 3.1 Pro costs $2.00 per million input tokens and $12.00 per million output tokens for prompts up to 200K, with a 90% caching discount to $0.20/M. Gemini's rates rise to $4.00/M input and $18.00/M output above 200K. Its 1M context window is twice Opus 4.8's 500K. For long-document analysis, RAG with large context, and multimodal tasks, Gemini's architecture has native advantages. Opus 4.8 counters with deeper reasoning, better instruction following, and Anthropic's mature tool-use ecosystem.
Verdict
For prompts up to 200K, Gemini charges $2.00/M input and $12.00/M output against Opus 4.8's $5.00 and $25.00. Gemini also wins cached input at $0.20/M against Opus's $0.50/M, with both applying a 90% discount. Gemini's 1M context window is twice Opus's 500K. Pick by workload shape. Large corpus or multimodal work leans Gemini, while deep multi-step reasoning leans Opus.
Which should you pick?
Choose Claude Opus 4.8
Deep reasoning tasks, complex code synthesis, multi-step planning, and workloads where instruction-following precision matters more than context size or per-token cost.
Choose Gemini 3.1 Pro
Large-context workloads up to 1M tokens, multimodal processing, long-document analysis, and teams prioritizing cost efficiency in the premium tier.