How LLM API Pricing Works

Tokens, input vs output, context windows — why the same task can cost 50× more on one model than another, explained simply.

HomeAI Models › Claude Opus 4.8 vs Gemini 3.1 Pro

Claude Opus 4.8 vs Gemini 3.1 Pro: price comparison

Real 2026 API prices side by side, with the total cost of a typical 10M-input / 3M-output monthly workload.

Price & cost at a glance

Claude Opus 4.8Gemini 3.1 Pro
Input / 1M tokens$15$2
Output / 1M tokens$75$12
Context window300K2000K
Cost — 10M in + 3M out$375$56

Green = cheaper / larger. Prices per 1M tokens, USD. Snapshot 2026 — verify with the provider.

Which is cheaper?

Gemini 3.1 Pro is the cheaper option on a 10M-in / 3M-out workload — about $56/mo versus $375 for Claude Opus 4.8 (~6.7× difference). Because output tokens are billed higher, the model with the lower output price usually wins as your responses get longer.

Run your own token mix in the cost calculator, or see each model in depth: Claude Opus 4.8 · Gemini 3.1 Pro.

Frequently asked

Is Claude Opus 4.8 or Gemini 3.1 Pro cheaper?

At a typical 10M input + 3M output tokens per month, Gemini 3.1 Pro costs about $56 versus $375 for Claude Opus 4.8 — Gemini 3.1 Pro is roughly 6.7x cheaper on this workload. Your ratio of input to output tokens changes the gap.

What's the price difference between Claude Opus 4.8 and Gemini 3.1 Pro?

Claude Opus 4.8 is $15/$75 per 1M input/output tokens; Gemini 3.1 Pro is $2/$12. Output tokens usually dominate a bill, so compare the output price first.

Which has the bigger context window, Claude Opus 4.8 or Gemini 3.1 Pro?

Claude Opus 4.8 supports about 300K tokens and Gemini 3.1 Pro about 2000K. A bigger window costs more per call because every token in context is billed.

Educational estimates — not affiliated with any provider.