Claude Sonnet 5 vs Gemini 3.1 Pro
Anthropic's Claude Sonnet 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.
Pricing checked against provider documentation on . How we verify
The short answer
Claude Sonnet 5 is the cheaper option — roughly 1.1x less on a blended workload, and it suits fast claude-quality reasoning at scale. Gemini 3.1 Pro justifies its premium when you need best price-to-reasoning ratio.
Anthropic • Claude 5
$2.00 / $10.00
/ 1M tokens (input / output)
The workhorse Claude tier: a full million tokens of context and adaptive thinking at $2/$10, which undercuts the previous Sonnet 4.6 generation by a third on input while raising the context ceiling fivefold. The default pick for latency-sensitive products that still want Claude's writing and tool-use behaviour.
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 effectively identical than Claude Sonnet 5 on input tokens.
Output price
Gemini 3.1 Pro is 20% more expensive than Claude Sonnet 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 Sonnet 5 | Gemini 3.1 Pro | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $4 | $4 | $0 |
| Moderate — 10M in / 2M out | $40 | $44 | $4 |
| Heavy — 100M in / 20M out | $400 | $440 | $40 |
Specification comparison
| Attribute | Claude Sonnet 5 | Gemini 3.1 Pro |
|---|---|---|
| Input (/ 1M tokens) | $2.00 | $2.00 |
| Output (/ 1M tokens) | $10.00 | $12.00 |
| Cached input | $0.20 | — |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-01 | 2025-06 |
| Relative latency | low | medium |
| Open weights | No | No |
| API model ID | claude-sonnet-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 Sonnet 5 if…
- Production chat and copilots
- Long-document analysis
- Tool-heavy agents needing fast turns
- Code review and PR automation
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 Sonnet 5 or Gemini 3.1 Pro cheaper?
Claude Sonnet 5 is cheaper. On a blended 3:1 input-to-output workload it costs about 1.1x less than Gemini 3.1 Pro.
Which has the larger context window, Claude Sonnet 5 or Gemini 3.1 Pro?
Gemini 3.1 Pro has the larger window at 1.05M tokens versus 1M.
Should I use Claude Sonnet 5 or Gemini 3.1 Pro?
Pick Claude Sonnet 5 for fast claude-quality reasoning at scale. Pick Gemini 3.1 Pro for best price-to-reasoning ratio. If cost dominates the decision, Claude Sonnet 5 wins; if you need the capability ceiling, benchmark both on your own evals before committing.