Claude Sonnet 5 vs Gemini 3.1 Pro: which API costs less?
Averaged across three realistic workloads, Claude Sonnet 5 is about 11% cheaper than Gemini 3.1 Pro. Below: raw rates and side-by-side monthly costs, computed from prices verified 2026-10-17 (we track what you are billed today, promos included).
Rates per 1M tokens
| Model | Input | Output | Cached input |
|---|---|---|---|
| Claude Sonnet 5Anthropic | $2 | $10 | $0.200 |
| Gemini 3.1 ProGoogle | $2 | $12 | $0.200 |
Claude Sonnet 5: The $2/$10 launch price became the standard price; the planned increase to $3/$15 was cancelled. Gemini 3.1 Pro: Preview; prompts up to 200K tokens; longer prompts cost $4/$18.
Monthly cost, side by side
| Workload | Claude Sonnet 5 | Gemini 3.1 Pro | Difference |
|---|---|---|---|
Customer-support chatbot 2M input + 0.5M output tokens/month, 60% of input served from prompt cache | $6.84 | $7.84 | Claude Sonnet 5 −13% |
RAG / document Q&A 20M input + 1M output tokens/month, 70% cached (shared context) | $24.80 | $26.80 | Claude Sonnet 5 −7% |
Agentic coding assistant 50M input + 5M output tokens/month, 80% cached (long sessions) | $78.00 | $88.00 | Claude Sonnet 5 −11% |
Your traffic looks different? Run your own numbers in the calculator.
FAQ
Which is cheaper: Claude Sonnet 5 or Gemini 3.1 Pro?
Across three realistic workloads (chatbot, RAG, agent), Claude Sonnet 5 works out about 11% cheaper than Gemini 3.1 Pro on average. Raw rates: Claude Sonnet 5 $2/$10 per 1M tokens vs Gemini 3.1 Pro $2/$12. Verified 2026-10-17.
Does prompt caching change the comparison?
Yes — cached input costs $0.200 on Claude Sonnet 5 and $0.200 on Gemini 3.1 Pro. Our scenario numbers already include realistic cache hit rates.
Is cheaper always better?
No. Price is one axis — model capability, context window and latency differ. This page answers only the cost question; benchmark quality on your own tasks before switching.