Claude Opus 5 vs Gemini 3.1 Pro
Anthropic's Claude Opus 5 and Google's Gemini 3.1 Pro both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Gemini 3.1 Pro is the cheaper option — roughly 2.2x less on a blended workload, and it suits best price-to-reasoning ratio. Claude Opus 5 justifies its premium when you need most teams' best claude starting point.
Anthropic • Claude 5
$5.00 / $25.00
/ 1M tokens (input / output)
A step change over Opus 4.8 on deep reasoning and long-horizon agentic work, at half Fable 5's price and with the freshest knowledge cutoff in the Claude line. Anthropic's own guidance is that most teams should benchmark Opus 5 before paying for Fable 5.
Google • Gemini 3.1
$2.00 / $12.00
/ 1M tokens (input / output)
Google's shipping flagship while 3.5 Pro remains unreleased, and the cheapest frontier model by a wide margin. It still tops several hard-reasoning boards including GPQA Diamond and ARC-AGI-2, making it the value choice for research-style workloads — provided you keep prompts under 200K tokens, where the price doubles.
Input price
Gemini 3.1 Pro is 60% cheaper than Claude Opus 5 on input tokens.
Output price
Gemini 3.1 Pro is 52% cheaper than Claude Opus 5 on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | Claude Opus 5 | Gemini 3.1 Pro | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $10 | $4 | $6 |
| Moderate — 10M in / 2M out | $100 | $44 | $56 |
| Heavy — 100M in / 20M out | $1,000 | $440 | $560 |
Specification comparison
| Attribute | Claude Opus 5 | Gemini 3.1 Pro |
|---|---|---|
| Input (/ 1M tokens) | $5.00 | $2.00 |
| Output (/ 1M tokens) | $25.00 | $12.00 |
| Cached input | $0.50 | — |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-05 | 2025-06 |
| Relative latency | medium | medium |
| Open weights | No | No |
| API model ID | claude-opus-5 | gemini-3.1-pro-preview |
| Status | stable | preview |
Gemini 3.1 Pro: Prompts over 200K tokens reprice to $4 input / $18 output per 1M.
Choose Claude Opus 5 if…
- Agentic engineering with a cost ceiling
- Deep research and analysis
- Test-time compute scaling
- Production assistants needing recent knowledge
Choose Gemini 3.1 Pro if…
- Hard reasoning and research tasks
- Long-context document and video analysis
- Native multimodal pipelines
- Cost-conscious frontier workloads
Frequently asked
Is Claude Opus 5 or Gemini 3.1 Pro cheaper?
Gemini 3.1 Pro is cheaper. On a blended 3:1 input-to-output workload it costs about 2.2x less than Claude Opus 5.
Which has the larger context window, Claude Opus 5 or Gemini 3.1 Pro?
Gemini 3.1 Pro has the larger window at 1.05M tokens versus 1M.
Should I use Claude Opus 5 or Gemini 3.1 Pro?
Pick Claude Opus 5 for most teams' best claude starting point. Pick Gemini 3.1 Pro for best price-to-reasoning ratio. If cost dominates the decision, Gemini 3.1 Pro wins; if you need the capability ceiling, benchmark both on your own evals before committing.