Claude Opus 5.5 vs Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview costs about half as much as Claude Opus 5.5 for normal agent prompts: $2 input and $12 output per 1M tokens against $4 and $20. Past 200K prompt tokens its rate rises to $4 and $18, close to Opus. We have no benchmark score for Gemini 3.1 Pro Preview to set against those for Opus 5.5.
Two prices on Gemini 3.1 Pro
Our feature session, with 80K-token prompts, costs $11.04 on Gemini 3.1 Pro Preview and $21.60 on Opus 5.5. A long agent day at 150K tokens per prompt is still under the threshold: $99 against $195, or $26.10 against $41.10 with 90% of prompts cached.
Filling the whole window once costs more on Gemini, $4.19 against $4.00, because a prompt over 200K tokens is billed at the higher rate.
Seven months apart
Gemini 3.1 Pro Preview was first listed on the API on 19 February 2026, and it is still a preview by its name. Anthropic released Opus 5.5 on 22 September 2026. Google's newer model is in Opus 5.5 against Gemini 4 Argon, with a Terminal-Bench score on both sides.
Size and what each reads
Gemini 3.1 Pro Preview reads up to 1.05M tokens and writes up to 66K in one reply; Opus 5.5 reads 1M and writes up to 128K. Gemini takes text, images, video, audio and PDF files, Opus text and images. Opus 5.5 scored 66.4% on Terminal-Bench 4.0 at xhigh effort, 54.4% on FrontierCode 1.1 and 67.7% on Humanity's Last Exam with tools.
Side by side
| Claude Opus 5.5 | Gemini 3.1 Pro Preview | |
|---|---|---|
| Maker | Anthropic | |
| Released | 22 September 2026[1] | 19 February 2026[2] first API listing |
| Context window | 1M tokens[1] | 1.05M tokens[3] |
| Max output | 128K tokens[1] | 66K tokens[3] |
| Input price | $4 per 1M tokens[1] | $2 per 1M tokens[4] |
| Output price | $20 per 1M tokens[1] | $12 per 1M tokens[4] |
| Cached input | $0.20 per 1M tokens[5] | $0.20 per 1M tokens[4] |
| Long prompts | One price | Over 200K: $4 in, $18 out[4] Prompts over 200K tokens are billed at the higher rate. |
| Price change | None announced | None announced |
| Open weights | No[1] Offered through the Claude API and cloud platforms; no weights are published. | No[6] Served through the Gemini API; no weights are published. |
| Reads | text, image[1] | text, image, video, audio, pdf[3] |
Benchmarks
None of the benchmarks below has a published score for both models. We only show a score we can cite with its source and date; "Not published" means we found none for that model, not that it scored zero.
| Benchmark | Claude Opus 5.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Terminal-Bench 4.0Agentic coding tasks in a real terminal. | 66.4%[7] Run at xhigh effort. | Not published |
| FrontierCode 1.1 (Main)Hard software engineering tasks. | 54.4%[7] Max effort. | Not published |
| Humanity's Last Exam (with tools)Expert-level questions across many fields, tools allowed. | 67.7%[7] | Not published |
What a coding session costs
Our own estimate from the list prices above, for three sessions we define: a coding agent resends the conversation with every call, so prompts are large and grow. "Cached" assumes 90% of prompt tokens are read from the prompt cache and leaves out cache write fees. A long-prompt price applies when a call's prompt is over its threshold. Work out your own mix with the token cost calculator.
| Session | Claude Opus 5.5 | Claude Opus 5.5 cached | Gemini 3.1 Pro Preview | Gemini 3.1 Pro Preview cached |
|---|---|---|---|---|
| Quick fix10 calls of 25K prompt and 1.5K output tokens | $1.30 | $0.45 | $0.68 | $0.28 |
| Feature session60 calls of 80K prompt and 2K output tokens | $21.60 | $5.18 | $11.04 | $3.26 |
| Long agent day300 calls of 150K prompt and 2.5K output tokens | $195 | $41.10 | $99 | $26.10 |
Value for money and release gap
Claude Opus 5.5 is dated 7 months later (215 days; Gemini 3.1 Pro Preview: first API listing). Price per point divides our feature-session cost by a published score: lower means more score for the money. It is a rough lens, not a ranking.
| Measure | Claude Opus 5.5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Input tokens per $1 | 250K | 500K |
| Filling the whole context window once | $4.00 | $4.19 |
Questions
Is Gemini 3.1 Pro cheaper than Claude Opus 5.5?
For prompts up to 200K tokens, yes: $2 per 1M input tokens and $12 per 1M output, against $4 and $20. Above 200K, Gemini 3.1 Pro Preview charges $4 and $18.
Which is better for coding, Opus 5.5 or Gemini 3.1 Pro?
We can't say from benchmarks. Opus 5.5 has published scores, including 66.4% on Terminal-Bench 4.0, and we found none for Gemini 3.1 Pro Preview that we could cite.
Which has the bigger context window?
Gemini 3.1 Pro Preview, at 1.05M tokens against 1M. Opus 5.5 writes longer replies: up to 128K tokens against 66K.
Most compared
Any other two models: pick them in the lists at the top of the page.
- Claude Opus 5.5 vs Claude Sonnet 5.5
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Opus 5 vs Claude Opus 5.5
- Claude Opus 5.5 vs GPT-6.1 Sol
- Claude Opus 5.5 vs GPT-5.6 Sol
- Claude Opus 5.5 vs GPT-6 Astra
- Claude Opus 5.5 vs Gemini 4 Argon
- Gemini 3.1 Pro Preview vs Gemini 4 Argon
- Claude Opus 5.5 vs Grok 4.7
- Claude Opus 5.5 vs DeepSeek V4 Pro
- Claude Sonnet 5 vs Claude Sonnet 5.5
- Claude Haiku 5.5 vs Claude Sonnet 5.5
- Claude Haiku 4.5 vs Claude Haiku 5.5
- Claude Fable 5 vs Claude Fable 5.1
- Claude Sonnet 5.5 vs GPT-6.1 Sol
- Claude Fable 5.1 vs GPT-6 Astra
- Claude Haiku 5.5 vs GPT-6 Luna
- GPT-6.1 Sol vs GPT-6 Sol
- GPT-6.1 Sol vs GPT-6 Astra
- Claude Sonnet 5.5 vs Gemini 4 Argon
- Gemini 4 Argon vs GPT-6.1 Sol
- Claude Haiku 5.5 vs Gemini 3.8 Flash
- Claude Sonnet 5.5 vs Kimi K3
- Claude Sonnet 5.5 vs GLM-5.3
More tools
Sources
- platform.claude.com: docs/en/models/opus-5-5/overview, read
- openrouter.ai: google/gemini-3.1-pro-preview, read
- ai.google.dev: gemini-api/docs/models/gemini-3.1-pro-preview, read
- ai.google.dev: gemini-api/docs/pricing, read
- platform.claude.com: docs/en/about-claude/pricing, read
- ai.google.dev: gemini-api/docs/models, read
- anthropic.com: claude-opus-5-5, read
Numbers from the makers' own pages, checked by hand, last read . List prices in US dollars before tax. Spotted a mistake? office@shuriken.sh.
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