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Gemini 3.8 Flash vs Claude Opus 5.5
Claude Opus 5.5 scores higher than Gemini 3.8 Flash on all 6 public leaderboards that rate both. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Gemini 3.8 Flash is at 41.3 and Claude Opus 5.5 at 90.9 (out of 100). On each maker's API, Gemini 3.8 Flash costs $0.75 / $3.75 per 1M tokens (input / output) and Claude Opus 5.5 $4 / $20.
Scores as published by each board; table composed November 13, 2026.
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Leaderboard by leaderboard
| Board | Gemini 3.8 Flash | Claude Opus 5.5 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,583.5 | 1,814.7 | Claude Opus 5.5 |
| LiveBench global average (0-100) | 57.3 | 83.4 | Claude Opus 5.5 |
| SimpleBench AVG@5 % (private set) | 82.4 | 88.4 | Claude Opus 5.5 |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 56 | 70.1 | Claude Opus 5.5 |
| Artificial Analysis intelligence index · measured runs only | 30.8 | 59.1 | Claude Opus 5.5 |
| Epoch AI Epoch Capabilities Index (ECI) · many benchmarks on one scale | 158.8 | 168.5 | Claude Opus 5.5 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Gemini 3.8 Flash is at 44.4 (#22 of 48) and Claude Opus 5.5 at 90 (#3). Claude Opus 5.5 scores higher on all 3 coding boards that rate both.
| Coding board | Gemini 3.8 Flash | Claude Opus 5.5 |
|---|---|---|
| LMArena · Coding | 1,510.1 | 1,543.4 |
| LiveBench · Coding | 73.3 | 87.1 |
| Vals Vibe Code Bench | 78.7 | 90.3 |
Gemini 3.8 Flash at a glance
- Developer
- Status
- Live since September 2, 2026
- API price
- $0.75 input / $3.75 output per 1M tokens · Google, gemini-3.8-flash
- Context window
- 1.05M tokens
Live — GA Sep 2 · $0.75/$3.75 per 1M introductory through Dec 31, identical to 3.7 · 1M in / 64K out · 'our most intelligent Flash model' · 20 days after 3.7.
Gemini 3.8 Flash is GA — same price as 3.7, twenty days later
2026-09-02 · Google released Gemini 3.8 Flash today. The Gemini API changelog for September 2 reads: "Gemini 3.8 Flash generally available (GA): Released gemini-3.8-flash, our most intelligent Flash model, engineered for long-horizon software engineering, autonomous agents, and complex enterprise workflows."
Claude Opus 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since September 22, 2026
- API price
- $4 input / $20 output per 1M tokens · Anthropic, claude-opus-5-5
- Context window
- 1M tokens
Live — Sep 22 · $4/$20 per MTok, down from Opus 5 at $5/$25 · 1M ctx / 128K out · adaptive thinking always on, default effort medium · cache reads 5% of base input · Anthropic now says start here for most workloads, and Opus 5 is legacy · fast mode (speed: 'fast', up to 2.5x the output tokens per second by Anthropic's figure) at $8 / $40 per MTok, double standard, left research preview Oct 15 with no waitlist, access request or beta header; on the Claude API and on Claude in Microsoft Foundry (Azure-hosted), not on Bedrock, Google Cloud, Claude Platform on AWS, the Batch API or Priority Tier; @ClaudeDevs says Google Cloud is coming soon (Anthropic's fast mode docs, read Oct 16).
AI models go live a median of 4 months after their knowledge ends: Claude Opus 5.5 knows up to June 2026, Gemini 4 Argon only to March
2026-11-06 · Of the 22 live AI models whose labs publish a knowledge cutoff, the median went live 4 months after its training data ends, by ArtificialWatch's count. The latest published cutoff we found is June 2026, for Anthropic's four current Claude models and OpenAI's GPT-6.1 Terra.
SemiAnalysis launches GDPx: Opus 5.5 leads at 12%, Gemini 4 Carbon close behind
2026-11-02 · SemiAnalysis released GDPx on November 2, a new agentic benchmark of 206 tasks across 11 domains, and the best model it tested scores 12%. Claude Opus 5.5 leads at 12.0, Gemini 4 Carbon is second at 10.9 and GPT-6 Astra third at 9.6. We read the leaderboard directly at gdpx.semianalysis.com.
Gemini 3.8 Flash vs Claude Opus 5.5: quick answers
Which is better, Gemini 3.8 Flash or Claude Opus 5.5?
It depends on what you measure. Claude Opus 5.5 scores higher than Gemini 3.8 Flash on all 6 public leaderboards that rate both. Claude Opus 5.5's widest lead is on LiveBench. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Gemini 3.8 Flash is at 41.3 and Claude Opus 5.5 at 90.9 (out of 100).
Which is newer, Gemini 3.8 Flash or Claude Opus 5.5?
Claude Opus 5.5. It went live on September 22, 2026, 20 days after Gemini 3.8 Flash (September 2, 2026).
Which is cheaper, Gemini 3.8 Flash or Claude Opus 5.5?
Gemini 3.8 Flash is cheaper on both input and output. On each vendor's own API, Gemini 3.8 Flash is $0.75 input / $3.75 output per million tokens and Claude Opus 5.5 is $4 input / $20 output per million tokens. Prices as published in the models.dev catalog, as of 2026-11-12.
Which has the bigger context window, Gemini 3.8 Flash or Claude Opus 5.5?
Gemini 3.8 Flash, at 1.05M tokens against Claude Opus 5.5's 1M, as each vendor lists it.
How do Gemini 3.8 Flash and Claude Opus 5.5 compare for coding?
On the ArtificialWatch coding index, Gemini 3.8 Flash is at 44.4 (#22 of 48) and Claude Opus 5.5 at 90 (#3). Claude Opus 5.5 scores higher on all 3 coding boards that rate both.
Who makes Gemini 3.8 Flash and Claude Opus 5.5?
Gemini 3.8 Flash is from Google; Claude Opus 5.5 is from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed November 13, 2026). Boards measure different things, so raw scores are only comparable within a row.
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Also: the bench index · API pricing · what a workload costs on each · the wire