Claude Opus 4.8 vs Gemini 3.1 Pro
Anthropic against Google, costed on the same three workloads. Gemini 3.1 Pro is cheaper on all three workloads.
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Monthly bill, side by side
| Workload | Claude Opus 4.8 | Gemini 3.1 Pro | Difference |
|---|---|---|---|
| Support chatbot 2,500 six-turn conversations a day |
$20,138 | $8,865 | $11,273 (2.3×) |
| Document summarizer 1,000 single-shot summaries a day |
$2,430 | $1,020 | $1,410 (2.4×) |
| Coding agent 200 twelve-turn sessions a day |
$14,040 | $5,976 | $8,064 (2.3×) |
No prompt caching and no batch discount on either side, so the comparison is like for like. Both figures assume 30 days a month.
The rate cards
| Claude Opus 4.8 | Gemini 3.1 Pro | |
|---|---|---|
| Input, per 1M tokens | $5 | $2 |
| Output, per 1M tokens | $25 | $12 |
| Cached input | $0.5 | $0.2 |
| Context window | 1M | 1.05M |
| Maximum output | 128K | 66K |
| Reasoning model | yes | yes |
| Vision | yes | yes |
Beyond the price
- Gemini 3.1 Pro reads up to 1.05M tokens of context in one request; Claude Opus 4.8 stops at 1M.
- Claude Opus 4.8 can write up to 128K tokens in one response, against 66K for Gemini 3.1 Pro.
- Only Claude Opus 4.8 offers a batch discount — 50% off both rates for work that can wait.
Run this comparison on your own numbers
Full detail: Claude Opus 4.8 pricing · Gemini 3.1 Pro pricing
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Common questions
Which is cheaper, Claude Opus 4.8 or Gemini 3.1 Pro?
Gemini 3.1 Pro is cheaper on all three workloads.
How much would Claude Opus 4.8 and Gemini 3.1 Pro cost each month?
On PromptSpend's standard workloads, per month: support chatbot: Claude Opus 4.8 $20,138, Gemini 3.1 Pro $8,865 (Gemini 3.1 Pro is cheaper by $11,273); document summarizer: Claude Opus 4.8 $2,430, Gemini 3.1 Pro $1,020 (Gemini 3.1 Pro is cheaper by $1,410); coding agent: Claude Opus 4.8 $14,040, Gemini 3.1 Pro $5,976 (Gemini 3.1 Pro is cheaper by $8,064). No prompt caching and no batch discount is assumed.
How do Claude Opus 4.8 and Gemini 3.1 Pro differ apart from price?
Gemini 3.1 Pro reads up to 1.05M tokens of context in one request; Claude Opus 4.8 stops at 1M. Claude Opus 4.8 can write up to 128K tokens in one response, against 66K for Gemini 3.1 Pro. Only Claude Opus 4.8 offers a batch discount — 50% off both rates for work that can wait.