AI model comparison
Claude Opus 5.5 vs Gemini 3.8 Flash
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Anthropic
Claude Opus 5.5
Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5.
- Input / 1M
- $4
- Output / 1M
- $20
- Context
- 1M
Gemini 3.8 Flash
Gemini 3.8 Flash is Google's most intelligent Flash model with significant gains from 3.7 Flash across software engineering, agentic tasks, and multi-step reasoning.
- Input / 1M
- $0.75
- Output / 1M
- $3.75
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Gemini 3.8 Flash
5.3x cheaper for a typical chat
Higher intelligence score
Claude Opus 5.5
57.6 vs 40.9 on Artificial Analysis
Larger context window
Gemini 3.8 Flash
1.05M vs 1M tokens
Newer release
Claude Opus 5.5
Released September 22, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Opus 5.557.6Gemini 3.8 Flash40.9Coding index
Claude Opus 5.5Not availableGemini 3.8 Flash76.3Agentic index
Claude Opus 5.5Not availableGemini 3.8 Flash40.2Pricing
Claude Opus 5.5 vs Gemini 3.8 Flash API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Opus 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Input tokensPer 1M tokens | $4 | $0.75 |
| Output tokensPer 1M tokens | $20 | $3.75 |
| Cached input (read)Per 1M tokens | $0.20 | $0.08 |
| Cache writePer 1M tokens | $5 | $0.04 |
| Web searchPer request | $0.01 | $0.014 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Claude Opus 5.5$18Gemini 3.8 Flash$3.38Coding task
30K in, 4K out
Claude Opus 5.5$200$86 cachedGemini 3.8 Flash$37.50$17.25 cachedLong document summary
150K in, 2K out
Claude Opus 5.5$640$70 cachedGemini 3.8 Flash$120$18.75 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Opus 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 66K tokens |
| Input types | File, Image, Text | Audio, File, Image, Text, Video |
| Output types | Text | Text |
| Reasoning effort levels | Max, Extra high, High, Medium, Low | High, Medium, Low |
| Default reasoning effort | High | Medium |
| Release date | September 22, 2026 | September 2, 2026 |
Features
Supported features
API features available for each model.
| Metric | Claude Opus 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Not supported | Supported |
| Verbosity control | Supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Claude Opus 5.5View full model details- Claude Opus 5.5 vs Claude Sonnet 5.5
- Claude Opus 5.5 vs Claude Fable 5.1
- Claude Opus 5.5 vs GPT-6 Astra
- Claude Opus 5.5 vs GPT-6.1 Sol
- Claude Opus 5.5 vs Claude Opus 5
- Claude Opus 5.5 vs Claude Fable 5
- Claude Opus 5.5 vs DeepSeek V4.1 Flash
- Claude Opus 5.5 vs Muse Spark 1.3
- Claude Opus 5.5 vs GLM 5.3 Flash
- Claude Opus 5.5 vs GPT-6 Sol
- Claude Opus 5.5 vs MiMo-V2.6-Flash
- Claude Opus 5.5 vs GPT-5.6 Sol
- Claude Opus 5.5 vs Hy4 preview
- Claude Opus 5.5 vs Grok 4.7
- Claude Opus 5.5 vs GPT-6 Luna
- Claude Opus 5.5 vs DeepSeek V4 Flash 0731
- Claude Opus 5.5 vs GLM 5.3
- Claude Opus 5.5 vs Kimi K3
- Claude Opus 5.5 vs DeepSeek V4 Flash 0423
- Claude Opus 5.5 vs Step 5 Preview
- Claude Opus 5.5 vs Hy3
- Claude Opus 5.5 vs Gemini 3.1 Pro Preview
Gemini 3.8 FlashView full model details- Gemini 3.8 Flash vs DeepSeek V4.1 Flash
- Gemini 3.8 Flash vs GLM 5.3 Flash
- Gemini 3.8 Flash vs MiMo-V2.6-Flash
- Gemini 3.8 Flash vs Hy4 preview
- Gemini 3.8 Flash vs GPT-6 Luna
- Gemini 3.8 Flash vs DeepSeek V4 Flash 0731
- Gemini 3.8 Flash vs GLM 5.3
- Gemini 3.8 Flash vs DeepSeek V4 Flash 0423
- Gemini 3.8 Flash vs Step 5 Preview
- Gemini 3.8 Flash vs Hy3
- Gemini 3.8 Flash vs GPT-5.6 Luna
- Gemini 3.8 Flash vs GPT-6 Astra
- Gemini 3.8 Flash vs Kimi K3
- Gemini 3.8 Flash vs Muse Spark 1.3
- Gemini 3.8 Flash vs Grok 4.7
- Gemini 3.8 Flash vs DeepSeek V4 Pro 0813
- Gemini 3.8 Flash vs Qwen3.8 Max (0902)
- Gemini 3.8 Flash vs Grok 4.6
- Gemini 3.8 Flash vs Claude Haiku 5.5
- Gemini 3.8 Flash vs GPT-5.6 Terra
- Gemini 3.8 Flash vs Claude Sonnet 5
- Gemini 3.8 Flash vs Claude Opus 4.8
- Gemini 3.8 Flash vs Ling 3.1 Flash
- Gemini 3.8 Flash vs Claude Opus 4.7
- Gemini 3.8 Flash vs Qwen3.8 2.4T A95B
- Gemini 3.8 Flash vs Gemini 3.7 Flash
- Gemini 3.8 Flash vs Muse Spark 1.2
- Gemini 3.8 Flash vs GPT-5.4
- Gemini 3.8 Flash vs Grok 4.5
- Gemini 3.8 Flash vs GPT-5.5
- Gemini 3.8 Flash vs Gemini 3.6 Flash
- Gemini 3.8 Flash vs Muse Spark 1.1
- Gemini 3.8 Flash vs Gemini 3.5 Flash
Our take
Gemini 3.8 Flash is 5.3x cheaper for a typical chat. Claude Opus 5.5 scores higher on the Artificial Analysis Intelligence Index (57.6 vs 40.9). Gemini 3.8 Flash has the larger context window (1.05M vs 1M tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Claude Opus 5.5 or Gemini 3.8 Flash cheaper?
Gemini 3.8 Flash is cheaper for a typical chat (2K input tokens and 500 output tokens). Gemini 3.8 Flash costs $0.75 per 1M input tokens and $3.75 per 1M output tokens, while Claude Opus 5.5 costs $4 per 1M input tokens and $20 per 1M output tokens.
Which has a bigger context window, Claude Opus 5.5 or Gemini 3.8 Flash?
Gemini 3.8 Flash supports up to 1.05M tokens of context, compared with 1M for Claude Opus 5.5.
Is Claude Opus 5.5 smarter than Gemini 3.8 Flash?
On the Artificial Analysis Intelligence Index, Claude Opus 5.5 scores 57.6 and Gemini 3.8 Flash scores 40.9, putting Claude Opus 5.5 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Claude Opus 5.5 and Gemini 3.8 Flash at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Claude Opus 5.5 and Gemini 3.8 Flash answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Claude Opus 5.5 and Gemini 3.8 Flash at the same time. Compare the answers side by side and keep the best one.